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OF 

FUEL  OIL  AND  STEAM 
ENGINEERING 

A  PRACTICAL  TREATISE  DEALING  WITH  FUEL 

OIL,    FOR    THE    CENTRAL   STATION    MAN,  THE 

POWER   PLANT   OPERATOR,  THE   MECHANICAL 

ENGINEER  AND  THE   STUDENT 


BY 
ROBERT  SIBLEY,  B.  S. 

EDITOR  JOURNAL   OP   ELECTRICITY    AND   WESTERN  INDUSTRY;    FORMERLY     PROFESSOR 

OF     MECHANICAL     ENGINEERING,     UNIVERSITY     OF     CALIFORNIA',     FELLOW 

AMERICAN    INSTITUTE    OF    ELECTRICAL     ENGINEERS;     MEMBER 

AMERICAN  SOCIETY   OF   MECHANICAL   ENGINEERS,   AND 

PAST-  PRESIDENT  OF  THE  SAN  FRANCISCO  SECTION 

AND 

C.  H.  DELANY,  B.  S.,  M.M.E. 

ASSISTANT   ENGINEER   OF   OPERATION,    PACIFIC   GAS   AND   ELECTRIC   COMPANY; 
MEMBER   AMERICAN   SOCIETY    OF   MECHANICAL   ENGINEERS 


SECOND  EDITION 


McGRAW-HILL  BOOK  COMPANY,  INC. 

NEW  YORK:    370  SEVENTH  AVENUE 

LONDON:    6  <k  8  BOUVERIE  ST.,  E.  C.  4 

1921 


/M 


*i  X*  V "-:  ,.: 


COPYRIGHT,  1921,  BY  THE 
McGRAw-HiLL  BOOK  COMPANY,  INC. 


COPYRIGHT,  1918,  BY  THE 
TECHNICAL  PUBLISHING  COMPANY 


THK  MAPI,  E  PRESS  YORK  PA 


DEDICATION 
To  THE  UNIVERSITY  OF  CALIFORNIA  AND  ITS  SPLENDID  TRADITIONS 

WHATEVER   IS   GOOD  AND   HELPFUL  WITHIN  THESE   PAGES    IS 
AFFECTIONATELY  DEDICATED  BY   THE   AUTHORS. 


PEEFACE  TO  SECOND  EDITION 

The  rapidity  with  which  the  first  edition  of  this  book  was  ex- 
hausted has  exceeded  the  fondest  expectations  of  its  writers. 
The  field  of  fuel  oil  in  its  uses  in  steam  electric  generation,  though 
an  important  one,  is  somewhat  narrow  in  the  number  of  people 
involved  in  its  study.  The  early  exhaustion  of  the  first  edition, 
however,  has  given  the  authors  an  opportunity  to  re-write  the 
book  and  to  add  many  new  and  interesting  advances  that  have 
been  made  during  the  three  year  period  since  the  first  edition 
appeared  upon  the  market. 

We  are  particularly  grateful  to  Prof.  L.  S.  Marks  of  Harvard 
University,  to  Prof.  W.  F.  Durand  of  Stanford  University;  Mr. 
C.  R.  Weymouth,  chief  engineer  of  Charles  C.  Moore  &  Co.; 
Messrs.  R.  J.  C.  Wood  and  H.  L.  Doolittle  of  the  Southern 
California  Edison  Company;  Mr.  E.  A.  Rogers,  chief  engineer  of 
steam  electric  generation  for  the  New  Cornelia  Copper  Co.; 
Mr.  E.  H.  Peabody,  consulting  engineer;  Prof.  E.  H.  Lockwood 
of  Yale;  Dr.  D.  S.  Jacobus,  advisory  engineer  of  the  Babcock 
and  Wilcox  Company;  and  Mr.  J.  E.  Woodbridge  of  Ford,  Bacon 
and  Davis,  for  valuable  information,  helpful  suggestions,  and  a 
kindly  and  encouraging  attitude  for  further  efforts  in  the  com- 
pilation of  this  work. 

Many  of  the  newer  portions  of  this  work  have  first  appeared  in 
print  either  in  the  columns  of  the  Electrical  World  or  the  Journal 
of  Electricity,  and  to  these  two  publications  we  are  grateful  for 
the  interest  and  kindly  suggestions  they  have  given  to  us. 

ROBERT  SIBLEY. 
C.  H.  DELANY. 

SAN  FRANCISCO, 
January,  1921. 


Vll 


X  PREFACE   TO   THE  FIRST  EDITION 

The  many  illustrative  problems  that  have  been  worked  out 
in  the  chapters  on  steam  engineering  and  boiler  economy  are 
based  upon  the  data  obtained  from  the  latest  edition  of  Marks  & 
Davis'  "  Tables  and  Diagrams  of  the  Thermal  Properties  of 
Saturated  and  Superheated  Steam/'  published  by  Longmans, 
Green  &  Company,  which  may  be  purchased  through  any 
reputable  book  dealer  for  the  sum  of  one  dollar.  For  a  careful 
study  of  these  illustrative  examples  the  reader  should  provide 
himself  with  a  copy  of  these  steam  tables,  although  this  is  not 
necessary  for  most  of  the  discussions  on  fuel  oil  and  furnace 
design  as  treated  in  the  text.  K 

The  six  beautiful  views  of  the  economy  measuring  apparatus 
installed  at  the  Long  Beach  Plant  of  the  Southern  California 
Edison  Company,  featured  in  this  book,  are  extended  through  the 
courtesy  of  R.  J.  C.  Wood,  superintendent  of  generation  for  the 
Southern  Division  of  that  company. 

Throughout  the  work  the  authors  have  attempted  to  set  forth 
standard  practice  in  fuel  oil  and  steam  engineering.  As  a  con- 
sequence they  are  indebted  to  a  large  group  of  manufacturers, 
engineers  and  power  plant  operators  for  their  timely  suggestions 
in  pointing  out  and  developing  the  fundamental  laws  of  fuel  oil 
and  steam  engineering  practice  that  are  dwelt  upon  in  this  work. 

ROBERT  SIBLEY. 
C.  H.  DELANY. 

SAN  FRANCISCO,  CAL., 
May  1,  1918. 


CONTENTS 

CHAPTER  I 

PAGE 

THE  MODERN  POWER  PLANT  FOR  FUEL  OIL  CONSUMPTION 1 

The  storage  tank — Pumps  for  storage  supply — The  hot-well — 
Feed-water  heaters — Feed-water  pumps — Economizers — The 
boiler — The  Superheater — The  separator — Reciprocating  engines 
or  steam  turbines — Condenser — Wet  vacuum  pumps — Dry 
vacuum  pumps. 

CHAPTER  II 

FUNDAMENTAL  LAWS  INVOLVED 14 

Newton's  laws  of  motion — Three  fundamental  units  of  length, 
mass  and  time — Velocity,  acceleration,  and  force  defined — Con- 
ception of  work  and  power — Various  types  of  energy  employed  for 
useful  work. 

CHAPTER  III 

THEORY  OP  PRESSURES 22 

The  steam  gage — The  difference  between  absolute  pressure  and 
gage  pressure — The  column  of  mercury — Vacuum  pressures — Con- 
fusion in  pressure  units — Relationship  of  pressure  units — Inches  of 
water  and  pounds  pressure  per  square  inch — The  thirty  inch 
vaccum — The  practical  formula  for  conversion  of  pressures 
—To  reduce  barometer  readings  to  the  standard  thirty  inch 
vacuum — Corrections  for  the  brass  scale  of  a  barometer — Example 
— Corrections  for  altitude  and  latitude. 

CHAPTER  IV 

MEASUREMENT  OF  TEMPERATURES 31 

Fixed  points  for  thermometer  calibration — The  various  tempera- 
ture scales  employed — Relationship  of  fahrenheit  and  centigrade 
values — Relationship  of  fahrenheit  and  reaumur  values — Relation- 
ship of  centigrade  and  reaumur  values — Methods  of  temperature 
measurement — Estimation  by  flame  color — The  melting  point 
of  metals  and  alloys — The  method  of  immersion — The  alcohol 
and  mercurial  thermometers — The  expansion  pyrometer — Electri- 
cal thermometers — The  radiation  pyrometer — Standardization 
and  testing  of  thermometers — The  stem  correction. 

xi 


xii  CONTENTS 

CHAPTER  V 

PAGE 

THE  ELEMENTARY  LAWS  OF  THERMODYNAMICS 42 

The  irrefutable  experiments  of  Davy — Joule's  complete  demon- 
stration of  the  mechanical  equivalent  of  heat — The  first  law  of 
thermodynamics — Boyle's  law — Charles'  law — The  absolute  scale 
—The  composite  law  of  gases — A  formula  for  gas  density — To 
compute  "R"  for  any  gas — Further  illustrative  examples. 

CHAPTER  VI 

WATER  AND  STEAM 50 

Three  states  are  possible  in  all  bodies — The  fundamental  principle 
in  steam  engineering — Steam  engineering  still  supreme — The  for- 
mation of  ice — Latent  heat  of  fusion — The  formation  of  steam — 
Latent  heat  of  evaporation — Other  variations  occur  with  changes 
of  pressure — Data  easily  taken  from  steam  tables — Total  heat  of 
steam — Total  heat  of  dry  saturated  steam — Other  instances  of  total 
heats. 

CHAPTER  VII 

THE  STEAM  TABLES 57 

The  steam  tables  as  adopted  in  this  discussion — Recapitulation  of 
fundamental  evaluations — Analysis  of  a  typical  page  of  steam 
tables — Temperatures  in  fahrenheit  units — Pressures  in  absolute 
notation — Pressures  in  atmospheres — Specific  volume — Specific 
density — The  heat  of  liquid — The  latent  heat  of  evaporation — 
Total  heat  of  dry  saturated  steam — Internal  and  external  work — 
Entropy  of  water — The  entropy  of  evaporation — Total  entropy — 
Tables  for  superheated  steam. 

CHAPTER  VIII 

How  TO  COMPUTE  BOILER  HORSEPOWER 66 

The  meaning  of  the  word  "rating" — The  development  of  the  word 
"horsepower" — The  boiler  horsepower — The  conversion  of  boiler 
horsepower  to  mechanical  horsepower  units — The  myriawatt  as  a 
basis  of  boiler  performance — Relationship  of  boiler  horsepower  and 
myriawatts — The  builder's  rating — To  compute  actual  boiler 
rating. 

CHAPTER  IX 

EQUIVALENT  EVAPORATION  AND  FACTORS  OF  EVAPORATION 73 

The  standard  that  has  been  adopted — Dry  saturated  steam — Wet 
saturated  steam — Superheated  steam — To  compute  the  boiler 
horsepower. 


CONTENTS  xiii 

CHAPTER  X 

PAGE 

How  TO  DETERMINE  QUALITY  OF  STEAM.   .    . 78 

Dry  saturated  steam — Superheated  steam — Computation  of  total 
heat  of  superheated  steam — Steam  calorimeters — The  determina- 
tion of  superheat — Determination  of  moisture  in  saturated  steam — 
The  barrel  or  tank  calorimeter — Surface  condenser  tank  calorimeter. 

CHAPTER  XI 

THE  STEAM  CALORIMETER  AND  ITS  USE 86 

The  chemical  calorimeter — The  throttling  calorimeter — The 
limitations  of  the  throttling  calorimeter — The  electric  calorimeter 
—The  separating  calorimeter — Correction  for  steam  used  by  calori- 
meter— The  sampling  nipple — Conclusions  on  moisture  measuring 
apparatus — Latent  heat  of  evaporation — A  second  formula  for  heat 
of  evaporation — Relationship  of  specific  volume  for  superheated 
steam — A  simplified  but  limited  formula — Other  relationships 
exist. 

CHAPTER  XII 

RATIONAL  AND  EMPIRICAL  FORMULAS  FOR  STEAM  CONSTANTS  ....  95 
The  value  of  formulas  in  steam  engineering — Relation  between 
temperature  and  pressure  of  saturated  steam — The  total  heat  of 
saturated  steam — Regnault's  formula — Henning's  formula — Latent 
heat  of  evaporation — A  second  formula  for  heat  of  evaporation — 
Relationship  of  specific  volume  for  superheated  steam — A  simpli- 
fied but  limited  formula — Other  relationships  exist. 

CHAPTER  XIII 

THE  FUNDAMENTALS  OF  FURNACE  OPERATION  IN  FUEL  OIL  PRACTICE.  100 
The  fundamentals  of  the  tea-kettle  and  the  boiler  are  the  same — 
Inefficiency  of  tea-kettle  operation — Efficiency  in  the  modern 
steam  boiler  a  necessity — Efficient  furnace  construction  of  utmost 
importance — Fuels  defined — An  air  supply  essential — Furnace 
operation — The  fuel  oil  burner  and  its  function — The  path  of  the 
furnace  gases — The  economizer  and  its  economic  value — Quality 
of  air  required — The  draft  gage  and  its  principle  of  operation — 
Apparatus  for  determining  ingredients  of 'outgoing  chimney  gases — 
Draft  regulating  devices — The  chimney. 

CHAPTER  XIV 

THE  BOILER  SHELL  AND  ITS  ACCESSORIES  FOR  STEAM  GENERATION.  .  107 
The  laws  of  heat  involved  in  steam  generation — The  principle  of 
operation  of  the  steam  boiler — Mathematical  equation  for  heat 
transference — Mathematical  law  for  total  heat  absorption — Rela- 
tionship of  rate  of  heat  transfer — Necessity  for  boiler  accessories — 
Injector  or  pump  for  feed  water  supply — Check  and  non-return 
valves — The  steam  gage  and  the  water  gage — Manholes — 
Provision  for  expansion— The  mud  drum — Safety  valve. 


XIV  CONTENTS 

CHAPTER  XV 

PAGE 

BOILER  CLASSIFICATION. .    .    115 

The  boiler  drum  and  tubes — Internally  and  externally  fired  boilers 
—The  return  tubular  boiler — The  fire  tube  and  the  water  tube 
boiler — Vertical  and  horizontal  types — Illustrations  of  principles 
of  construction  and  operation — The  Babcock  and  Wilcox  boiler — • 
The  Parker  boiler — The  Stirling  type — The  Heine  type — Marine 
boilers. 

CHAPTER  XVI 

FUEL  OIL  AND  SPECIFICATIONS  FOR  PURCHASE 124 

Advantages  of  crude  petroleum  as  a  fuel — Liquid  fuels  classified — 
Physical  and  Chemical  properties  of  oil — Odor  and  color — Moisture 
— Sulphur,  gas  and  other  ingredients — Specifications  for  the  pur- 
chase of  oil. 

CHAPTER  XVII 

FUEL  OIL  PRICES  AND  OIL  PRODUCTION      .    .   135 

Price   fluctuation — Decreasing   supply — A  necessary  development. 

CHAPTER  XVIII 

THE  SAFE  OPERATION  OF  STEAM  BOILERS.    ..'•... 141 

Inspection  tests  involved — Preliminary  precautions — Connecting 
up  boiler  units — Low  water  encountered — Avoid  making  repairs 
under  pressure — Removal  of  sediment — Keep  out  cylinder  oil — 
Cooling  and  cleaning  the  boiler — Putting  boiler  out  of  service. 

CHAPTER  XIX 

How  TO  COMPUTE  STRENGTH  OF  BOILER  SHELLS 147 

The  strength  of  the  solid  plate — The  strength  of  the  net  section — 
Resistance  to  shear — Resistance  to  compression — Efficiency  of  the 
riveted  section — Gage  pressure  necessary  to  burst  the  solid  boiler 
plate — Bursting  pressure  of  the  seam — The  safe  working  pressure — 
Example  of  a  lap  joint,  longitudinal  or  circumferential,  double- 
riveted. 

CHAPTER  XX 

FURNACES  IN  FUEL  OIL  PRACTICE 155 

Fuel  oil  furnace  operation — The  commercial  furnace — Location 
of  burners — Service  for  one  burner  only — Large  furnaces. 

CHAPTER  XXI 

BURNER  CLASSIFICATION  IN  FUEL  OIL  PRACTICE 166 

The  inside  mixer — The  outside  mixer — An  example  of  the  mechani- 
cal atomizer — The  home-made  type  of  burner. 


CONTENTS  XV 

CHAPTER  XXII 

PAGE 

MECHANICAL  ATOMIZING  OIL  BURNERS 174 

Koerting  burner — Dahl  burner — Peabody  mechanical  burner — 
Moore  shipbuilding  company  burner — Coen  burner. 

CHAPTER  XXIII 

RULES  FOR  EFFICIENT  OPERATION  OF  OIL  FIRED  BOILERS 189 

Regulate  air  to  suit  load — Prevent  air  leakage  through  setting — 
Analyze  flue  gases  frequently — Burner  must  be  suited  to  furnace — 
Keep  boilers  clean  and  maintain  furnaces  properly — Regulate 
atomizing  steam  to  suit  oil — Heat  oil  to  proper  temperature  for 
atomization — Boilers  should  not  be  forced  excessively — Shutting 
down  boilers  for  short  periods  should  be  avoided — Oil  should  not  be 
sprayed  into  furnace  unless  there  is  a  fire — Feed  water  uniformly — 
Keep  boilers  clean  and  in  good  repair — Maintain  baffles  and  flame 
plates  in  good  condition — Use  recording  instruments  wherever 
practicable — Determine  efficiency  daily  from  records — Fire  boilers 
scientifically. 

CHAPTER  XXIV 

FUEL  OIL  BURNING  APPLIANCES 202 

Storage  tanks — Measurement  of  oil — Oil  pumps — Strainers — 
Oil  heaters — Oil  burners — Oil  piping — Automatic  regulators — 
The  Witt  improved  oil  burner  governor — The  Moore  automatic 
fuel  oil  regulator — The  Merit  automatic  oil  stoking  system. 

CHAPTER  XXV 
CHANGING  FROM  COAL  TO  OIL 221 

CHAPTER  XXVI 

THE  GRAVITY  OF  OILS  IN  FUEL  OIL  PRACTICE 227 

The  method  of  the  Westphal  balance  for  exact  measurement — 
Details  of  procedure — Computations  involved. 

CHAPTER  XXVII 

MOISTURE  CONTENT  OF  OILS 235 

Summary  of  methods  employed  in  determining  the  moisture  con- 
tent— The  approximate  method  of  treatment — Error  in  assuming 
percentage  by  weight  is  same  as  percentage  by  volume. 

CHAPTER  XXVIII 

DETERMINATION  OF  HEATING  VALUE  OF  OILS ...   241 

An  approximate  method  based  on  the  Baurne/  scale — Dulong's 
formula  based  on  the  ultimate  analysis — The  fuel  calorimeter — The 


xvi  CONTENTS 

PAGE 

Parr  calorimeter — The  principle  of  operation — Detailed  operation 
of  the  Parr  calorimeter — Preliminary  precautions — The  explosion 
of  the  charge  and  the  taking  of  temperatures — The  correction  for 
temperature  readings — Higher  and  lower  heating  value. 

CHAPTER  XXIX 

THEORY  OF  CHIMNEY  DRAFT 251 

The  law  of  pressures  in  chimney  draft — The  theoretical  draft — 
Draft  formula  for  the  modern  power  plant — An  example  of  chim- 
ney design  for  sea-level  installation — Corrections  in  chimney  height 
for  altitude — Rule  for  altitude  correction — An  example  of  chimney 
design  at  altitude. 

CHAPTER  XXX 

ACTUAL  DRAFT  REQUIRED  FOR  FUEL  OIL 265 

Draft  losses  in  steam  power  generation — Loss  of  draft  in  boilers — 
Loss  in  flues  and  turns — Total  available  draft  required — Artificial 
draft. 

CHAPTER  XXXI 

CHIMNEY  GAS  ANALYSIS 271 

The  taking  of  the  flue  gas  samples  and  analysis — Orsat  apparatus — 
To  ascertain  the  carbon  dioxide  content  of  a  flue  gas — To  ascertain 
the  oxygen  content  of  a  flue  gas — To  ascertain  the  carbon  monoxide 
content  of  a  flue  gas — To  ascertain  the  nitrogen  content  of  a  flue  gas 
— An  approximate  check  on  the  Orsat  analysis — Chemical  formulas 
for  preparing  the  absorption  solutions — The  Hemphel  apparatus  for 
determining  the  hydrogen  content — Gas  analysis  in  the  power  plant 
— Conclusion  on  the  Orsat  analysis. 

CHAPTER  XXXII 

ANALYSIS  BY  WEIGHT,  AND  AIR  THEORETICALLY  REQUIRED  IN  FUEL  OIL 

FURNACE 279 

Relationship  of  a  component  weight  to  the  whole — Fundamental 
laws  involved — A  concrete  rule  for  conversions — Weight  of  air 
theoretically  required  for  perfect  fuel  oil  combustion — Correction 
for  hydrogen  appearing  in  fuel  analysis — Oxygen  theoretically 
required  for  fuel  combustion — Air  required  per  pound  of  fuel 
burned. 

CHAPTER  XXXIII 

COMPUTATION  OF  COMBUSTION  DATA  FROM  THE  ORSAT  ANALYSIS.    .   286 
Air  actually  supplied  to  furnace  per  pound  of  fuel  burned — An 
illustrative  example — A  second  formula  for  ascertaining  air  actually 
admitted  to  the  furnace — Weight  of  dry  flue  gas  per  pound  of  fuel — 
Ratio  of  air  drawn  into  furnace  to  that  theoretically  required. 


CONTENTS  xvii 

CHAPTER  XXXIV 

PAGE 

WEIGHING  WATER  AND  OIL 295 

Volumetric  method  of  measurement — Method  of  standardized 
platform  scales — Weighing  of  the  oil — Sampling  the  oil  supply — 
General  sampling  of  fuel  oil  for  purchase — Sampling  with  a  dipper 
— Continuous  sampling — Mixed  samples. 

CHAPTER  XXXV 

MEASUREMENTS  OF  STEAM  USED  IN  ATOMIZATION 302 

Mathematical  expression  for  flow  of  steam — Apparatus  employed 
in  measuring  steam  in  atomization — Calibration  of  orifice — 
Numerical  illustration. 

CHAPTER  XXXVI 

THE  TAKING  OF  BOILER  TEST  DATA 307 

The  object — The  instructions  for  boiler  tests — The  test  for  effi- 
ciency under  normal  rating — Time  of  duration  of  test — The  begin- 
ning and  stopping  of  a  test — The  weighing  of  the  water — The  heat 
represented  in  the  steam  generated — The  oil,  its  measurement  and 
analysis — The  steam  used  in  atomization — The  boiler  efficiency — 
The  overload  test — The  quick  steaming  test — Observations  neces- 
sary— Pressure  readings — Temperature  readings — The  flue  gas  an- 
alysis— The  test  as  a  whole. 

CHAPTER  XXXVII 

PRELIMINARY  TABULATION  AND  CALCULATION  OF  TEST  DATA    .    .    .    .314 
The  log  sheet  for  weighing  the  water — Log  sheet  for  the  fuel  oil  fed 
to  furnace — Other  data  to  be  taken — The  general  log  sheet — The 
plotting  of  the  test  data. 

CHAPTER  XXXVIII 

THE  HEAT  BALANCE  AND  BOILER  EFFICIENCY 320 

Total  heat  absorbed  by  boiler — Heat  absorbed  by  boiler  for 
atomization — Net  heat  absorbed  by  boiler  for  power  generation — 
Loss  due  to  moisture  in  the  fuel — Loss  due  to  moisture  formed  by 
burning  hydrogen — Loss  due  to  heat  carried  away  in  dry  gas — 
Loss  due  to  incomplete  combustion — Loss  due  to  evaporating  steam 
for  atomization — Loss  due  to  superheating  steam  used  for  atomiza- 
tion— Total  loss  in  atomization— Loss  due  to  moisture  in  entering 
air — Stray  losses — Summary  of  heat  balance — Net  boiler  efficiency 
— Boiler  efficiency  as  a  steaming  mechanism — Summary  of  data 
used. 


xviii  CONTENTS 

CHAPTER  XXXIX 

PAGE 

SUMMARY     OF     SUGGESTIONS    FOR     FUEL     OIL    TESTS    AND    THEIR 

TABULATION .,.    .    .    .  329 

Efficiency  for  oil  fired  boilers  defined — Tabluation  of  fuel  oil  test 
data — Principal  data  and  results  of  boiler  test. 

CHAPTER  XL 

THE  USE  OF  EVAPORATIVE  TESTS  IN  INCREASING  EFFICIENCY  OF  OIL 

FIRED  BOILERS    .    .  \. 337 

Furnace  arrangement — Oil  burners — Draft — Flue  gas  analysis  for 
maximum  efficiency — Regulation — Records — Practical  illustra- 
tions of  economy  study — General  furnace  arrangement — Table 
showing  economy  data — Comparative  economic  results — Conclu- 
sions from  test  data. 

CHAPTER  XLI 

ECONOMIES  OBTAINED  IN  OIL  BURNING  PRACTICE 351 

Economics  in  the  New  Cornelia  Copper  Company  plant  type 
of  equipment — Boiler  efficiency — Operation  of  automatic  regula- 
tors— Maintaining  economy — Motor-generator  sets. 

CHAPTER  XLII 

MISCELLANEOUS  OIL  BURNING  TESTS 368 

General — Description  of  plant — Method  of  testing — Boiler  tests — 
Boiler  efficiency — Stack  temperatures — Oil  consumed — Steam  to 
burners — Pressure  loss  in  superheater — Varying  draft — Ratio  of 
oil  and  steam  pressures — Radiation  test — Swinging  load — Starting 
up  cold — Tests  on  flow  of  oil  through  burners — Influence  of  load  on 
pressures  of  oil  and  atomizing  steam  in  oil  burners — Tests  with 
oil  burners — Practical  application  of  test  data. 

CHAPTER  XLIII 

PRESENT  STATUS  OF  OIL  BURNING  POWER  PLANT  DESIGN 386 

Fuel — Location  of  steam-electric  power  plants — Size  of  steam 
plant  units — Automatic  control. 

APPENDIX  I 

ILLUSTRATIVE  PROBLEMS .  400 

Thirty-three  examples  solved  in  detail,  illustrating  the  computa- 
tions involved  in  economy  tests  for  oil  fired  boilers — Miscellaneous 
questions  and  answers. 

APPENDIX  II 
HELPFUL  FACTORS  IN  FUEL  OIL  STUDY  AND  CONSERVATION 411 


CONTENTS  xix 

APPENDIX  III 

PAGE 

RULES  AND  REQUIREMENTS  OF  THE  NATIONAL  BOARD  OF  FIRE  UNDER- 
WRITERS FOR  THE  STORAGE  AND  USE  OF  FUEL  OIL  AND  FOR 
THE  CONSTRUCTION  AND  INSTALLATION  OF  OIL  BURNING 
EQUIPMENTS,  ALSO  FUEL  OIL  RULES  FOR  THE  CITY  OF  NEW 
YORK.  415 

APPENDIX  IV 

USEFUL  INFORMATION 434 

APPENDIX  V 
BRIEF  BIBLIOGRAPHY  ON  FUEL  OIL 444 


FUEL  OIL  AND  STEAM 
ENGINEERING 


CHAPTER  I 

THE   MODERN   POWER   PLANT   FOR   FUEL   OIL   CON- 
SUMPTION 

| HE  enormous  growth  of  the  electrical 
industry  throughout  the  world  dur- 
ing the  past  decade  has  entirely 
revolutionized  methods  of  power 
development.  Especially  is  this  true 
west  of  the  Rocky  Mountains,  where 
gigantic  natural  waterpowers  have 
been  put  to  a  useful  purpose.  Owing 
to  the  fact,  however,  that  most  of 
the  western  streams  show  a  great 
variation  in  flow  in  the  different 
seasons  of  the  year,  it  is  not  always 
possible  to  depend  solely  upon  water- 
power  for  the  supply  of  electrical 
energy.  In  recent  years  the  advent 
of  crude  petroleum  upon  the  Pacific 

Coast,  representing  a  total  annual  production  of  over  one  hundred 
million  barrels,  has  made  it  possible  when  rainfall  or  water  supply 
is  lacking  to  economically  supply  the  needed  power.  During  cer- 
tain hours  of  the  day,  too,  when  the  so-called  peak  load  con- 
ditions are  to  be  met  by  a  central  station,  additional  electrical 
energy  over  that  possible  to  supply  from  the  hydro-electric  station 
is  found  to  be  necessary.  Hence,  the  steam  power  plant,  con- 
sisting of  large  concentrated  units,  is  now  recognized  as  an  in- 
dispensable auxiliary  to  continuity  of  service. 

In  order  that  there  should  be  no  excessive  loss  in  distribution, 
these  concentrated  steam  power  units  are  usually  found  in  the 

1 


FIG.  1.— A  20,000  h.p.  Curtis 
turbine  installed  in  San  Fran- 
cisco. 


&ri,.a*#2*  STEAM  ENGINEERING 


FIG.  2. — Exterior  view  Long  Beach  Plant,  Southern  California  Edison  Com- 
pany. This  plant  is  noted  for  its  use  of  meters,  for  various  sorts  of  economy 
studies  and  for  records  obtained  in  daily  operating  practice.  Note  the  finish 
and  aesthetic  beauty  of  the  exterior. 


MODERN  POWER  PLANT  FOR  OIL  CONSUMPTION          3 

heart  of  the  great  distribution  centers.  Especially  is  this  true 
where  abundance  of  circulating  or  cooling  water  may  be  obtained. 
Thus  we  find  in  Central  California,  Station  A  and  Station  C  of 
the  Pacific  Gas  &  Electric  Company,  and  the  Fruitvale  Station 
of  the  Southern  Pacific  Company,  all  situated  in  the  distributing 
centers  of  San  Francisco  and  its  immediate  vicinity.  In  the 
Los  Angeles  district  we  find  that  the  Redondo  and  Long  Beach 
plants  of  the  Southern  California  Edison  Company,  owing  to  the 
lack  of  abundant  cooling  water  near  the  distribution  center  are 
situated  at  a  distance  from  it  of  some  fifteen  or  twenty  miles. 

It  will  now  be  interesting  and  instructive  to  examine  the  details 
of  a  typical  power  installation  of  the  sort  just  hinted  at. 

First,  we  shall  describe  the  so-called  steam  cycle  or  the  journey 
of  the  steam-making  water  from  the  time  it  enters  the  steam 
boiler  until  it  has  passed  through  the  turbine,  or  power  unit,  and 
returned  again  to  the  boiler;  secondly,  we  shall  consider  the  cir- 
culating water  which  is  necessary  in  large  quantities  to  convert 
the  exhaust  steam  back  again  into  water;  and  thirdly,  we  shall 
also  touch  briefly  upon  the  journey  of  the  oil  from  the  time  it 
leaves  the  cars  at  the  sidetrack  until  it  disappears  from  the  chim- 
ney as  a  flue  gas.  We  shall  also  touch  briefly  upon  the  general 
size  and  functions  of  apparatus  employed  to  accomplish  these 
results. 

THE  STEAM  CYCLE 

The  Storage  Tank. — The  supply  of  water  for  steaming  pur- 
poses is  usually  brought  to  a  make-up  or  storage  tank  from  supply 
wells  either  on  the  immediate  premises  or  nearby  property.  If 
these  are  not  found,  it  is  brought  from  rivers,  lakes,  or  other 
bodies  in  the  vicinity,  or  in  many  cases  is  purchased  from  some 
water  company  supplying  the  municipality.  The  storage  tanks 
are  varied  in  size,  shape  and  capacity  from  a  small  tank,  used  as 
a  receiver  and  hot- well,  to  a  number  of  tanks,  large  and  small, 
used  for  storage  purpose  only. 

The  use  of  storage  tanks  depends  upon  the  source  and  quantity 
of  water  supplied  and  the  load  carried  by  the  plant.  Where  there 
is  a  steady  and  positive  source  of  supply,  the  tank  may  be  of  small 
capacity.  In  some  cases  where  the  supply  is  small  and  the 
storage  at  different  periods  is  unfit  for  use,  larger  storage  and 
settling  tanks  are  required,  and  at  times  even  filtration  and 
cleaning  tanks  also  are  employed. 


FUEL  OIL  AND  STEAM  ENGINEERING 


/|W||N  -«*t>Q«>*.Q>ti: 


MODERN  POWER  PLANT  FOR  OIL  CONSUMPTION  5 

Pumps  for  Storage  Supply. — The  tanks  above  alluded  to  are 
filled  either  by  pumps,  gravitation  flow,  siphons,  or  piping  from 
a  water  company's  main.  There  seems  to  be  no  standard  type 
of  pump.  Both  reciprocating  and  rotary  appear  in  standard 
practice.  On  the  other  hand,  many  plants  have  wells  and  water 
is  lifted  by  air  pressure.  This,  on  account  of  the  total  absence 
of  working  parts,  is  particularly  useful,  where  there  are  a  number 
of  scattered  wells,  and,  also, 
when  it  becomes  necessary  to 
handle  dirty  water,  that  is, 
water  containing  sand,  grit, 
and  dirt  in  suspension.  This 
air  lift  consists  of  a  partially 
submerged  water  pipe  and  an 
air  supply  pipe.  The  casing 
of  the  well  is  driven  below 
the  lift  pipe.  The  lift  pipe 
is  set  in  the  well  either  with 
air  surrounding  it  between 
the  pipe  and  the  casing,  or 
with  a  cap  over  the  casing, 
making  the  space  in  the  casing 

air-tight.      In  some  instances    FIG.  4. — Measuring  and  purifying  tank  for 

the  well  casing  is  used  directly          water  SUPP^  at  Redondo  plant, 
as  the  lift  pipe. 

The  Hot- Well. — The  water  from  the  storage  tanks  is  either 
pumped  or  is  caused  to  flow  by  gravity  to  a  socalled  hot-well. 
The  hot-well  is  a  tank  which  stores  the  water  before  it  passes  to 
the  feed-water  heater.  It  receives  water  from  the  condenser 
and  admits  an  additional  supply  from  the  storage  tanks  to  meet 
the  needs  of  steam  generation. 

Feed-Water  Heaters. — From  the  hot-well,  water  is  taken 
into  the  feed-water  heater.  The  function  of  a  feed-water  heater 
is  to  heat  the  entering  water  to  a  temperature  approximating  that 
of  evaporating  conditions  in  order  to  keep  the  boiler  at  as  even  a 
temperature  as  possible  and  at  the  same  time  to  put  the  exhaust 
steam  from  the  auxiliary  apparatus  to  some  useful  purpose. 

Feed-water  heaters  are  divided  into  two  general  types:  open 
and  closed.  In  the  open  heater  the  steam  comes  in  direct  con- 
tact with  the  cooling  water,  and  if  there  is  a  sufficient  quantity 
of  exhaust  steam,  it  raises  the  water  to  212°F.,  the  excess  steam 


6 


FUEL  OIL  AND  STEAM  ENGINEERING 


passing  to  the  atmosphere.  In  a  closed  heater,  on  the  other 
hand,  the  water  and  steam  do  not  come  in  contact  with  each 
other,  the  water  usually  passing  through  a  set  of  tubes  while  the 
steam  is  brought  in  contact  with  the  outside  of  the  tubes. 

Feed-Water  Pumps. — The  water  is  forced  into  the  boiler  by 
means  of  feed-water  pumps,  which  may  be  either  ordinary  re- 
ciprocating or  multistage  centrifugal  pumps,  the  latter  being 
especially  adapted  to  large  power  plants. 


FIG.  5. — The  Redondo  Power  Plant  of  the  Southern  California  Edison  Company 
with  oil  storage  tanks. 

• 

In  steam  plants  where  closed  feed-water  heaters  are  used,  the 
boiler  feed  pumps  are  placed  before  the  heater,  thus  pumping 
through  the  heater  to  the  boiler.  When  open  feed-water  heaters 
are  used,  however,  the  boiler  feed  pumps  are  placed  between  the 
heater  and  the  boiler. 

Economizers. — Economizers  are  sometimes  installed  as  well 
as  feed- water  heaters.  The  economizer  is  a  series  of  pipes  through 
which  the  feed-water  passes,  placed  in  the  path  of  escaping  gases 
from  the  boiler. 

The  Boiler. — The  boiler  next  receives  the  water  from  these 
heaters  and  converts  it  into  steam  at  the  desired  pressure  and 


MODERN  POWER  PLANT  FOR  OIL  CONSUMPTION 


temperature.  The  main  types  of  boilers  are  water  and  fire  tube. 
Modern  practice  indicates  a  decided  preference  for  water  tube 
boilers.  A  water  tube  boiler  consists  of  steam  and  water  drums 
placed  on  the  top  and  a  mud  drum  placed  below,  the  two  being 
connected  by  a  series  of  tubes  filled  with  water  or  steam.  The 
fire  is  below  these  tubes,  and  the  heat  from  the  furnace  is  made  to 
pass  around  them  several  times  by  means  of  baffles  or  partitions, 
thus  supplying  heat  for  steam  generation. 


H 


FIG.  6. — Cross-section  of  the  Babcock  &  Wilcox  Boiler — oil-fired — with  Pea- 
body  furnace. 

The  Superheater. — The  water  being  thus  converted  into 
saturated  steam  by  heat  from  the  furnace  of  the  boiler,  is  next 
passed  through  a  series  of  tubes  known  as  a  superheater.  These 
tubes  are  exposed  in  a  heated  portion  of  the  gas  passage  and  thus 
the  steam  is  raised  to  a  point  much  higher  than  its  saturated 
temperature. 

The  Separator. — From  the  superheater  the  steam  passes 
through  suitable  piping  to  a  separator,  placed  between  the  boiler 
and  the  engine,  or  between  the  boiler  and  the  turbine.  This 
separator  is  placed  as  near  the  power  unit  as  possible  in  order  to 


8  FUEL  OIL  AND  STEAM  ENGINEERING 

remove  all  condensed  steam  that  may  be  found  in  the  pipes.  One 
form  of  separator  performs  its  function  by  quickly  reversing  the 
direction  of  the  flow  of  steam,  thus  depositing  the  water  into 
a  drip  which  is  drained  off  into  the  condenser.  Another  form  gives 
a  rotary  motion  to  the  entering  steam  thus  hurling  particles  of 
water  off  by  centrifugal  force  and  collecting  it  in  proper  recep- 
tacles. Again,  baffle  plates  are  at  times  employed  wherein  the 
flow  is  interrupted  by  corrugated  or  fluted  plates,  and  the  par- 
ticles of  water  adhering  to  these  are  then  drained  off. 

Reciprocating  Engine  or  Steam  Turbines. — The  steam  next 
goes  from  the  separator  to  the  main  power  generating  units. 
The  main  units  in  earlier  practice  were  reciprocating  engines ;  in 
modern  installations  they  are  steam  turbines. 

Reciprocating  engines  may  be  divided  into  several  classes,  the 
details  of  which  will  not  be  outlined  in  this  general  discussion. 
Suffice  it  to  say,  however,  that  the  main  principle  upon  which 
reciprocating  engines  act  is  that  steam  enters  a  cylinder  under 
pressure,  thus  forcing  ahead  a  piston  which  is  connected  to  a 
crank  arm,  thereby  causing  rotation  and  the  consequent  genera- 
tion of  power. 

Steam  turbines  are  divided  into  two  general  classes  known  as 
impulse  turbines  and  reaction  turbines.  In  the  impulse  turbine 
steam  is  allowed  to  expand  in  passing  through  a  nozzle,  thus  caus- 
ing the  steam  to  travel  at  an  enormous  velocity.  The  steam, 
having  acquired  this  velocity,  by  impinging  against  movable 
blades,  causes  rotation  and  the  consequent  generation  of  power. 
In  the  reaction  turbine,  however,  the  steam  is  allowed  to  enter  the 
buckets  or  rotating  vanes  at  a  comparatively  low  velocity, 
These  vanes  are  so  designed  that  the  steam  may  expand  in  this 
movable  portion  and  by  means  of  its  expanding  pressure  cause 
rotation  and  hence  the  generation  of  power. 

Turbines  as  a  general  rule  have  two  other  classifications,  known 
as  vertical  and  horizontal.  The  vertical  turbine  revolves  upon  a 
vertical  shaft,  which  is  supported  at  the  bottom  by  a  thin  film 
of  oil  under  the  high  pressure  of  about  900  to  1000  Ib.  per  in. 
The  horizontal  turbine,  however,  as  the  name  indicates,  rotates 
on  a  horizontal  axis,  and  is  supported  in  the  usual  manner  by 
means  qf  suitable  bearings. 

Condenser. — From  the  steam  turbine,  the  steam,  having  ex- 
panded to  its  useful  limit,  is  dropped  into  an  incasement  through 
which  cool  water  is  being  passed.  Upon  coming  in  contact  with 


MODERN  POWER  PLANT  FOR  OIL  CONSUMPTION  9 

this  cooling  device  the  steam  is  again  converted  into  water.  The 
apparatus  performing  this  function  is  known  as  a  condenser, 
there  being  two  general  classes:  surface  condensers  and  jet 
condensers. 

In  the  surface  condenser  the  steam  from  the  turbine  and  the 
cooling  water  from  a  nearby  source  of  supply  do  not  come  into 
direct  contact,  but  the  cooling  water  is  passed  through  inclosed 
tubes  around  which  the  steam  from  the  turbine  or  power  unit  is 
made  to  pass.  This  type  of  condenser  is  used  where  large 
quantities  of  water  are  available  for  cooling  purposes  but  not 
for  steaming  purposes.  Thus  the  use  of  salt  water,  the  only 
abundant  supply  available  for  ocean-going  steamships  and  large 
power  plants  situated  near  the  ocean,  makes  a  condenser  of  the 
surface  type  imperative  for  such  installation. 

In  the  jet  condenser  the  supply  of  cooling  water  is  allowed  to 
mingle  with  the  steam  as  it  drops  from  the  turbine  or  power  unit 
and  thus  the  steam  is  at  once  condensed  into  water.  The  water 
from  the  jet,  if  the  supply  is  pure,  may  be  used  in  the  hot-well 
for  steam  purposes. 

Wet  Vacuum  Pumps. — The  condensed  steam,  now  in  the  form 
of  water,  is  pumped  from  the  condenser  back  again  into  the  hot- 
well  by  means  of  what  is  known  as  the  wet  vacuum  pump.  This 
pump  may  be  either  a  reciprocating  or  rotary  pump,  but  in 
general  the  rotary  type  seems  to  have  the  preference.  Thus  the 
entire  cycle  for  the  water  is  traced  from  the  make-up  tank  or 
hot-well  through  the  boiler  and  power  unit,  and  back  again  to  the 
hot-well. 

Dry  Vacuum  Pumps. — The  condenser  also  has  a  dry  vacuum 
pump  in  order  to  remove  from  the  steam  space  within  any  air 
which  may  have  been  trapped  from  the  steam  generated  in  the 
boiler.  This  pump  is  nothing  more  nor  less  than  an  ordinary 
air  compressor  so  designed  that  it  will  take  air  at  a  very  low 
pressure  and  compress  it  up  to  atmospheric  pressure,  thus  pump- 
ing, as  it  were,  into  the  outer  atmosphere  such  air  as  may  have 
been  entrapped  in  the  condenser. 

CIRCULATING  WATER  CYCLE 

From  the  description  of  the  working  of  the  condenser  it  is 
seen  that  cooling  water  is  necessary  to  convert  the  steam  in  the 
condenser  back  again  into  water.  This  cooling  supply  is  known 


10  FUEL  OIL  AND  STEAM  ENGINEERING 

as  circulating  water,  which  is  usually  taken  through  pipes  from 
some  large  natural  lake  or  river  or  even  the  ocean  and  forced  by 
means  of  reciprocating  or  centrifugal  pumps  through  the  con- 
denser back  again  into  the  open.  The  water  in  its  journey  is 
raised  in  temperature  in  the  surface  condenser  system  from  15 
to  20°F.  above  its  entering  condition. 

THE  OIL  CYCLE 

Of  general  interest  to  boiler  testing  and  operation  is  the 
cycle  employed  in  the  utilization  of  crude  petroleum  as  a  fuel. 
Let  us  then  briefly  trace  the  journey  the  oil  makes  through  the 
modern  power  plant. 


FIG.  7. — The  Staples  &  Pfeifer  fuel  oil  atomizer. 

In  the  larger  installations  the  oil  is  sidetracked  from  the  main 
railway  line  in  specially  designed  cars  or  barges  for  its  easy  con- 
veyance and  handling.  An  oil  heater,  consisting  of  a  coil  through 
which  steam  is  passing,  is  lowered  into  the  car  in  order  to  warm 
the  oil  as  it  is  drawn,  thus  making  its  transfer  considerably 
easier.  By  means  of  a  pump  this  oil  is  then  taken  into  a  storage 
tank  which  may  be  of  wood,  steel,  or  concrete,  depending  upon 
the  permanence  of  design  thought  necessary.  From  this  storage 
ta,nk  the  oil  is  pumped  through  oil  heaters,  the  exhaust  from  the 
pumps  in  many  cases  being  utilized  in  still  further  heating 
oil  before  it  reaches  the  burner  or  atomizer. 

An  atomizer  is  a  device  used  to  vaporize  or  spray  the  oil  into 
the  furnace  in  fine  globules  or  particles.  This  is  accomplished 
by  means  of  steam,  air,  or  some  mechanical  contrivance.  Im- 
mediately upon  its  being  sprayed  into  the  furnace  carefully 
designed  air  regulating  devices  admit  sufficient  air  from  below  to 
cause  perfect  combustion.  The  heat  thus  liberated  from  the  oil 
due  to  its  burning  with  the  oxygen  is  caused  to  flow  in  and  around 


MODERN  POWER  PLANT  FOR  OIL  CONSUMPTION 


11 


12 


FUEL  OIL  AND  STEAM  ENGINEERING 


numerous  tubes  through  which  water  is  passing  and  thus  this 
water  is  converted  into  steam.  After  passing  these  tubes  the 
heated  flue  gases  brought  to  life  by  the  burning  of  the  oil  with  the 
entering  air  are  then  conducted  through  the  chimney  out  into 
the  atmosphere. 

An  interesting  detail  in  the  boiler  plant  is  the  automatic 
system  of  firing  employed  to  minimize  labor  and  improve  effi- 
ciency in  burning  the  oil.  The  Moore  patent  fuel  oil  regulating 
system  which,  from  one  central  point,  controls  the  oil  supply, 
the  atomizing  steam  and  the  amount  of  air  to  each  furnace,  is  an 
interesting  example. 


FIG.  9. — Moore  steam  to  burner  regulator. 

This  regulator  is  actuated  by  the  pressure  from  the  main  steam 
header  so  that  any  variation  in  steam  requirements  will  cause  a 
corresponding  change  in  the  amount  of  oil  fired,  due  to  an  increase 
or  decrease  in  the  steam  supply  to  the  oil  pumps  and  atomizers. 
Any  fluctuation  in  steam  pressure  operates  a  governor  whose 
power  arm  controls  a  bleeder  valve  on  the  oil  pump  discharge  line, 
thus  cutting  off  the  oil  supply  if  the  steam  pressure  is  too  high 
and  increasing  it  if  too  low.  Any  change  in  pressure  in  the  oil 
main,  in  turn,  controls  the  amount  of  steam  for  atomizing  and 
of  air  for  burning  the  oil. 

It  is -found  that  a  simple  straight  line  relationship  exists  be- 
tween the  amount  of  steam  required  for  atomizing  the  oil  and  the 


MODERN  POWER  PLANT  FOR  OIL  CONSUMPTION        13 

amount  of  oil  burned.  Two  diaphragms  arc  employed  to  balance 
the  pressures  in  the  oil  main  and  in  the  steam  main  connected  to  the 
burners.  Any  difference  in  oil  pressure  operates  a  rotary  chrono- 
meter valve  in  the  steam  main  through  the  medium  of  a  fulcrum, 
water  motor  and  lever  connecting  rod.  Likewise  the  variance 
in  oil  pressure  actuates  a  counterweighted  rock  shaft  which  moves 
the  dampers  so  as  to  vary  the  amount  of  air  admitted  for 
combustion. 

GENERAL  SUMMARY 

Thus  it  is  seen  in  this  brief  description  that  by  using  crude  oil 
as  fuel  three  main  cycles  of  operation  are  synchronously  carried 
on  in  the  modern  power  plant.  Briefly  summarizing,  these  are 
as  follows: 

Water  is  taken  through  the  boiler,  converted  into  steam  and 
passed  through  a  driving  mechanism,  after  which  the  steam  is 
reconverted  into  water  and  this  water  again  passed  through  the 
boiler.  Simultaneously  with  this  action  water  is  being  pumped 
through  the  circulating  system  to  bring  about  the  conversion  of 
the  steam  from  the  power  unit  into  water.  Again  oil  in  a  finely 
atomized  or  gaseous  state  is  being  fed  through  pipes  into  the  fur- 
nace, where  it  immediately  combines  with  the  proper  quantity  of 
oxygen  from  the  entering  air,  and  thus  sufficient  heat  is  liberated 
from  the  oil  to  evaporate  the  water  supply  of  the  boiler  into  steam 
for  power  generation. 


CHAPTER  II 


FUNDAMENTAL  LAWS  INVOLVED  IN  STEAM 
ENGINEERING 

N  the  awful  throes  of  the  French 
Revolution  and  the  immediate 
years  following,  the  old  saying 
that  "  every  cloud  has  its  silver 
lining"  proved  true  in  certain 
lines  of  scientific  advancement, 
for  the  metric  system  of  units  was 
conceived  and  put  into  practice  at 
that  period. 

Our  modern  system  of  Arabic 
numerals,  now  practically  uni- 
versally adopted  throughout  the 
civilized  world,  required  over  five 
•  hundred  years  of  human  fumbling 
and  competition  with  the  old 
Roman  method  of  numerical  rep- 
resentation, before  a  complete  replacement  was  accomplished, 
so  intensely  are  we  all  creatures  of  habit  and  slaves  to  tradition. 
And  so  it  is  that  although  a  period  of  a  century  is  now  passed 
since  the  institution  of  the  metric  system,  modern  central  sta- 
tion engineering  practice  is  still  entangled  with  Fahrenheit 
scales,  boiler  horsepowers,  mechanical  horsepowers,  myriawatts, 
Baume  scale  readings  for  gravity,  inches  of  mercury  vacuum, 
pounds  pressure  per  sq.  in.,  feet  and  inches — all  units  related  so 
unscientifically  and  empirically  as  to  cause  bewilderment  in  itself. 
In  the  following  discussion,  however,  the  authors  will  endeavor 
to  set  forth  the  various  units  of  expression  in  such  simple  lan- 
guage that  it  is  hoped  that  even  the  beginner  may  have  little 
difficulty  in  understanding  their  meaning.  Let  us  first  get  some 
conception  of  the  need  for  units  of  measurement  and  how  such 
units  are  fundamentally  conceived. 

14 


FIG.     10. — Mechanical    energy    in 
reciprocating  units  at  Redondo. 


FUNDAMENTAL  LAWS  15 

Newton's  Laws  of  Motion. — Fable  has  it  that  Sir  Isaac  New- 
ton, when  a  boy  in  England  lying  one  day  under  an  apple  tree 
and  gazing  upward,  saw  an  apple  fall  to  the  ground.  The  con- 
templation of  this  phenomenon  led  Newton  to  give  to  the  world 
three  fundamental  laws  upon  which  modern  engineering  science 
is  built.  Briefly  these  laws  are  as  follows : 

Law  1.  Every  body  continues  in  a  state  of  rest  or  a  state  of  uniform 
motion  in  a  straight  line  except  in  so  far  as  it  may  be  compelled  by  force  to 
change  that  state. 

Law  2.  Change  of  motion  is  proportional  to  impressed  force  and  takes 
place  in  the  direction  of  the  straight  line  in  which  the  force  acts. 

Law  3.  To  every  action  there  is  always  an  equal  and  contrary  reaction; 
or  the  mutual  actions  of  any  two  bodies  are  always  equal  and  oppositely 
directed. 

Hence  a  force  is  said  to  be  acting  according  to  Law  1  whenever 
the  physical  conditions  are  such  that  velocity  is  changed  in 
magnitude  or  direction.  Thus,  when  a  train  of  cars  is  started 
or  stopped,  a  force  is  necessary  to  cause  this  phenomenon,  and 
this  is  evidently  a  change  in  the  magnitude  of  the  velocity.  On  the 
other  hand,  in  the  rotation  of  a  fly  wheel,  the  velocity  may  change 
solely  in  direction  without  a  change  in  magnitude,  and  yet 
a  force  be  necessary  to  maintain  its  parts  in  equilibrium.  Hence 
a  force  may  be  considered  as  a  push  or  a  pull  acting  upon  a  definite 
portion  of  a  body,  but  this  tendency  may  be  counteracted  in  whole 
or  in  part  by  the  action  of  other  forces.  In  the  latter  instance 
the  force  is  usually  denoted  as  pressure,  and  it  is  the  considera- 
tion of  this  latter  case,  or  the  consideration  of  pressures,  that  will 
largely  concern  our  attention  in  the  generation  of  steam  in  a 
boiler. 

Three  Fundamental  Units  of  Length,  Mass  and  Time. — In 
considering  Law  2,  it  is  seen  that  there  is  some  inherent  property 
in  matter  that  makes  it  difficult  to  set  it  in  motion.  Physicists 
have  defined  this  quality  of  matter  as  being  the  inertia  of  a  body. 
Inertia  is  expressed  quantitatively  in  engineering  practice  in 
terms  of  its  mass,  which  is  measured  in  pounds.  In  order  that 
these  quantities,  force  and  mass,  now  introduced  may  be  quan- 
titatively measured,  it  is  necessary  to  have  some  fundamental 
units  upon  which  to  base  our  computations.  Three  units  only 
are  fundamentally  required;  namely,  a  unit  of  length,  a  unit  of 
mass,  and  a  unit  of  time.  Scientific  practice  has  deduced  for 
these  units  the  centimeter,  the  gram,  and  the  second,  which  are 


16 


FUEL  OIL  AND  STEAM  ENGINEERING 


well  known  and  need  no  further  illustration.  In  engineering  prac- 
tice, however,  especially  among  English-speaking  people,  the 
foot,  the  pound,  and  the  second  seem  to  be  in  almost  universal 
usage.  We  shall  consequently  largely  express  our  deductions  in 
terms  of  these  latter  units. 

Velocity,  Acceleration,  and 
Force  Defined. — Having  now 
decided  upon  the  three  funda- 
mental units  of  measurement, 
let  us  look  into  other  funda- 
mental definitions  and  second- 
ary units  to  be  employed. 

Since  engineering  science 
must  deal  with  motion  and  the 
change  of  motions  per  unit  of 
time,  it  is  necessary  that  we 
have  units  wherein  to  measure 
£hem.  Change  of  distance  per 
unit  of  time  is  known  as  ve- 
locity and  is  expressed  in  feet 
per  second.  A  change  in  dis- 
tance may,  however,  be 
undergoing  a  change,  and  this 
phenomenon  is  known  as  ac- 
celeration, which  is  measured  by  the  change  of  velocity  in  feet 
per  second. 

Since  a  force  P  is  fundamentally  defined  as  being  proportional 
to  the  change  in  motion  of  a  body,  it  follows  that  a  force  is  equal 
to  a  constant,  M,  multiplied  by  the  change  in  motion,  or,  in 
other  words,  multiplied  by  the  acceleration,  a. 

When  M  is  in  pounds  mass  and  a  is  acceleration  in  ft.  per  sec. 
per  sec.,  the  force  P  is  measured  in  poundals.  The  pound  force 
is  the  unit,  however,  that  has  been  universally  adopted  in  engi- 
neering practice.  The  pound  is  such  a  force  as  will  give  to  a 
pound  mass  the  same  change  of  motion  per  second  as  is  acquired 
by  a  body  falling  freely  to  the  earth's  surface.  A  body  falls  to 
the  earth's  surface  with  an  acceleration  of  g  ft.  per  sec.  per  sec., 
wherein  g  has  an  average  value  of  about  32.16.  We  have  then 
the  fundamental  mathematical  expression  for  force  in  pounds  as 
follows : 

P  =  Ma 


FIG.  11. — Electrical  energy  from  steam 
turbine  in  San  Francisco. 


FUNDAMENTAL  LA  WS  17 

Whenever,  however,  it  is  necessary  to  ascertain  the  mass  M 
in  pounds  from  the  known  weight  W  of  the  body  in  lb.,  it  is 
necessary  of  course  to  divide  W  by  g  in  order  to  ascertain  the 

W 

mass.     Thus  we  have  in  this  caseP  =  — a  (la) 

u 

Thus,  if  an  automobile  weighing  3000  lb.  accelerates  from  a 
stand-still  to  forty  miles  per  hour  in  fifteen  seconds,  we  compute 
the  force  required  to  accomplish  this  as  follows: 

3000          40X5280 
"32.16  X  60X60  X15" 

Since  this  total  force  must  be  supplied  from  the  engine  cylinder 
this  now  gives  us  a  preliminary  clew  as  to  how  the  total  engine 
cylinder  area  is  to  be  proportioned. 

Engineers  oftentimes  find  a  more  direct  method  of  deriving  the 
laws  of  motion  by  considering  that  the  resistance  which  a  body 
offers  to  its  rate  of  change  in  velocity  is  called  its  inertia.  The 
word  "mass"  has  been  invented  as  a  quantitative  unit  -by  which 
inertia  may  be  measured;  hence  we  may  forget  any  particular 
physical  meaning  of  the  word  "mass"  and  consider  it  merely  as 
a  constant,  the  same  as  the  Greek  letter  «  enters  into  the  area  of 
a  circle  or  its  circumference,  when  speaking  of  them  in  reference 
to  the  diameter. 

Mr.  William  Kent,  the  late  author  of  Kent's  "Mechanical 
Engineers  Pocketbook, "  was  the  first  to  discuss  this  in  scientific 
magazines,  and  it  has  later  been  used  with  much  effectiveness  and 
clearness  by  consulting  engineers  in  establishing  the  fundamentals 
of  mechanics. 

Bodies  acquire  different  changes  of  motion  per  second,  or,  in 
other  words,  different  accelerations  at  different  points  on  the 
earth's  surface.  A  formula  has  been  established  by  means  of 
which  proper  corrections  may  be  made.  A  concrete  illustration 
of  this  will  appear  in  the  next  chapter  wherein  a  mercury  column 
is  used  to  measure  atmospheric  and  vacuum  pressures  at  differ- 
ent latitudes  and  altitudes. 

It  is  unfortunate  that  mass  and  force  have  the  same  unit  of 
expression,  for  they  are  definite  distinct  physical  concepts  and 
should  be  carefully  distinguished  in  order  to  avoid  confusion. 

Conception  of  Work  and  Power. — In  Law  2  we  are  informed 
that  the  change  of  motion  takes  place  in  the  direction  of  the 
straight  line  in  which  the  force  acts.  It  is  often  convenient  to 
note  quantitatively  the  product  of  the  force  and  the  distance 


18 


FUEL  OIL  AND  STEAM  ENGINEERING 


.a  8 


.2  o 


Is 


II 

a  °» 


FUNDAMENTAL  LAWS 


19 


through  which  the  force  acts.  This  product  is  called  "work" 
and  is  numerically  computed  by  multiplying  the  force  in  pounds 
by  the  distance  in  feet  through  which  the  force  acts.  The  re- 
sulting computations  are  then  expressed  in  foot-pounds  (ft.-lb.) 
Thus,  if  the  mean  effective  pressure,  P,  in  a  cylinder  is  measured 
in  pounds  per  sq.  in.  and  the  piston  has  an  area  of  A  sq.  in.,  it 
follows  that  the  total  force  or  pressure  acting  in  the  direction 
of  the  motion  of  the  piston  is  PA .  When  this  force  has  pushed  the 
piston  the  length  of  its  stroke,  L  ft.,  the  work  accomplished  is 


FIG.  13. — The*  steam  gage  tester  illustrates  the  application  of  a  fundamental 
law,  wherein  a  pressure  is  balanced  against  the  force  due  to  gravity. 

PL  A  ft.  lb.,  since  this  is  the  product  of  the  force  and  the  distance 
through  which  the  force  acts.  If  there  are  N  working  strokes 
per  minute,  the  ft.  lb.  of  work  accomplished  every  minute  are 
now  seen  to  be  PLAN. 

The  mention  of  the  words  "per  minute"  in  the  last  statement 
now  indicates  to  us  that  the  time  taken  to  perform  a  given 
quantity  of  work  in  engineering  practice  is  of  vast  importance. 
Consequently  this  fact  necessitates  still  another  unit  of  measure- 
ment, namely  that  of  power.  Power  is  denned  as  the  time  rate 
of  doing  work.  The  horsepower  is  the  basic  unit.  When  550 
ft.  lb.  of  work  are  performed  per  sec.,  or  33,000  ft.  lb.  per  minute, 


20 


FUEL  OIL  AND  STEAM  ENGINEERING 


a  horsepower  is  said  to  be  developed.  Hence,  since  in  the  above 
engine  cylinder  PLAN  ft.  Ib.  per  min.  are  being  developed,  the 
horsepower  is  computed  as  follows : 

PLAN 


H.P.  = 


(2) 


33,000 

Thus,  in  Alameda,  California,  a  certain  Diesel  oil  engine  has  a 
piston  area  of  113.15  sq.  in.,  a  stroke  of  1.5  ft.,  a  mean  effective 
pressure  of  77.3  Ib.  per  sq.  in.,  and  each  cylinder  makes  125 
working  strokes  per  minute.  Hence,  each  cylinder  develops 

77.3  X  1.5  X  113.15  X  125 


H.P. 


=  50.0 


33,000 

In  a  later  discussion  the  particular  power  units  employed  in 
steam  engineering  practice  will  be  considered  in  minute  detail, 
such,  for  instance,  as  the  horsepower,  the  boiler  horsepower,  and 
the  myriawatt. 

Various  Types  of  Energy  Em- 
ployed for  Useful  Work. — An- 
other important  consideration  is 
that  of  the  physical  character- 
istic of  a  body  which  enables  it 
to  perform  work.  This  physical 
quality  possessed  by  a  body 
which  enables  it  to  perform  a 
definite  quantity  of  work  is 
spoken  of  as  its  energy.  Energy 
then  is  the  capacity  for  work. 
In  general  we  meet  with  two 
great  classes  of  energy.  One  is 
that  of  kinetic  energy,  or  energy 
of  motion.  According  to  Law 
2,  if  the  motion  of  a  body  be 
changed,  a  force  is  required. 
Hence  a  body  actually  in  mo- 
tion possesses  kinetic  energy. 
The  other  type  of  energy  is 
known  as  potential,  or  energy 
of  position.  Thus  steam  moving  with  a  high  velocity,  by  the 
nature  of  its  kinetic  energy,  is  enabled  to  drive  the  wheels  of 
an  impulse  turbine.  On  the  other  hand,  crude  petroleum  when 
heated  so  that  it  will  unite  with  the  oxygen  of  the  air  gives  out 


FIG.  14. — The  safety  valve  shows 
the  possibility  of  safety  application, 
when  pressures  become  unbalanced. 


FUNDAMENTAL  LAWS  21 

energy  in  the  form  of  heat,  which  may  be  caused  to  do  useful 
work.  The  energy  inherently  latent  in  the  crude  pertroleum  is 
known  then  as>  potential  energy.  Engineering  practice  is  largely 
concerned  with  the  harnessing  of  various  forms  of  energy.  Look- 
ing about  us  in  nature  and  in  modern  engineering  accomplish- 
ment, we  may  see  numerous  instances  of  energy.  The  steam 
engine  and  steam  turbine  indicate  a  form  of  mechanical  energy; 
the  incandescent  light,  or  the  dynamo,  that  of  electrical  energy; 
the  evolving  of  heat  in  the  burning  of  crude  oil,  that  of  chemical 
energy;  the  human  conducting  of  affairs,  that  of  human  energy; 
the  rays  of  light  from  the  sun,  dissipating  eternally  10,000  h.p. 
over  each  acre  of  the  earth's  surface,  that  of  solar  energy,  and 
so  on  indefinitely.  Modern  investigation  has  conclusively  estab- 
lished the  fact  that  all  types  of  energy  are  interchangeable,  and 
though  some  types  of  energy  are  more  readily  convertible  into 
other  types,  yet  the  basic  law  is  true  that  no  energy  in  sum  total 
is  ever  destroyed,  and  on  this  basis,  or  law,  known  as  conservation 
of  energy,  practically  all  of  our  engineering  formulas  and  compu- 
tations are  evolved. 

The  conversion  of  the  chemical  energy  of  crude  oil  into  heat 
energy  of  the  furnace  and  thence  into  steam  largely  concerns  our 
attention  in  this  discussion.  Thus  each  pound  of  California 
crude  oil  will  be  found  in  later  articles  to  contain  approximately 
18,500  British  thermal  units  of  heat  energy.  This  energy  of  one 
pound  of  oil  when  wholly  converted  into  mechanical  energy  is 
sufficient  to  lift  a  person  weighing  150  pounds  through  a  vertical 
skyward  journey  of  some  18  miles.  Hence  the  study  of  the  ap- 
plication of  such  enormous  reservoirs  of  energy,  latent  in  crude 
petroleum,  will  prove  intensely  interesting  and  instructive. 

Bearing  in  mind  these  fundamental  laws,  we  should  now  be 
able  to  see  mentally  the  exact  changes  of  energy  that  are  going  on 
in  the  modern  power  plant;  first  as  chemical  energy  in  oil,  next 
as  latent  heat  energy  in  furnace  gases,  then  as  latent  heat  energy 
in  steam,  next  as  energy  of  motion  in  the  moving  parts  of  the 
power  generating  apparatus,  where  the  final  transformation  into 
electrical  energy  is  brought  about. 


CHAPTER  III 
THEORY  OF  PRESSURES 

N"  the  preceding  discussions  we 
have  seen  that  a  force  is  said  to 
be  acting  whenever  the  physical 
conditions  are  such  that  the 
velocity  of  a  body  tends  to  be 
changed  in  magnitude  or  direc- 
tion. If  two  opposing  forces  are 
equally  balanced,  there  is  simply 
a  tendency  to  change  motion  and 
such  a  force  is  known  as  a  pres- 
sure. This  opposing  force  in  the 
case  of  a  gas  or  vapor  under 
pressure  is  supplied  by  the  walls  of 
the  -containing  vessel.  Pressures 
then  constitute  an  important  phase 
of  steam  engineering  practice. 

The  Steam  Gage. — In  steam 
engineering  practice  heavy  pres- 
sures, that  is  pressures  above  the  atmosphere,  are  usually  meas- 
ured by  means  of  an  instrument  known  as  a  steam  gage.  This 
gage  consists  of  a  piece  of  hollow  metal  bent  into  a  circular  shape 
which,  under  pressure,  tends  to  straighten  out,  see  Fig.  16.  This 
straightening  effect  is  proportional  to  the  pressure  under  which 
the  boiler  is  working.  A  rack  and  pinion  movement,  placed  on 
the  end  of  this  curved  piece  of  metal  in  the  steam  gage,  causes 
the  needle  of  the  gage  to  indicate  pressure  readings.  By  compar- 
ing this  gage  with  a  definite  standard  its  accuracy  is  ascertained. 
The  Difference  Between  Absolute  Pressure  and  Gage  Pres- 
sure.— There  is  a  point  at  which  a  gas  is  said  to  exert  no  pressure. 
This  expanded  condition  of  a  gas  has  never  been  wholly  realized 
in  practice,  yet  this  very  beginning  point  or  zero  value  is  most 
convenient  in  expressing  pressure  valuations  and  such  denota- 
tions are  known  as  absolute  pressure  values.  The  steam  gage 
attached  to  the  boiler  does  not  read  absolute  pressure  values,  but 

22 


FIG.  15. — The  thermometer  suspen- 
sion for  barometer  correction. 


THEORY  OF  PRESSURES 


23 


such  pressure  readings  are  known  as  pounds  pressure  per  sq.  in. 
(gage)  which  means  that  one  must  add  the  absolute  pressure  of 
the  atmosphere,  Pa,  to  the  gage  reading,  Pg,  in  order  to  ascer- 
tain the  true  absolute  pressure  P  under  which  the  boiler  in  gen- 
erating steam.  Thus 

P    =    Pa    +   Pg  (1) 


FIG.  16.  —  Interior  and  exterior  view  of  steam  gage,  showing  principle  of  operation. 

Thus,  if  a  pressure  gage  of  the  steam  boiler  reads  186.4  per  Ib. 
sq.  in.  and  the  pressure  of  the  atmosphere  is  found  to  be  14.6 
Ib.  per  sq.  in.,  the  absolute  pressure  under  which  the  boiler  is 
operating  is 

p  =  186.4  +  14.6  =  201.0  Ib.  per  sq.  in. 

The  Column  of  Mercury.  —  The  most  accu- 
rate method  of  measuring  small  pressures  such 
as  the  pressure  of  the  atmosphere  and  con- 
denser vacuum  pressure  is  by  means  of  a 
vertical  column  of  mercury.  In  its  simplest 
form  this  consists  of  a  long  glass  tube  closed 
at  one  end  and  filled  with  mercury.  The 
tube  is  then  inverted  and  the  open  end  placed 
in  a  vessel  of  mercury  exposed  to  the  atmos- 
phere or  condenser  as  the  case  may  be,  as 

Shown  in  Fig.    18. 

In  the  case  of  atmospheric  pressure  determi- 
nation  the  mercury  will  at  once  lower  itself  in 
the  long  tube  until  the  height  of  enclosed  mercury  above  that 
in   the   vessel  is   sufficient   to   balance  the  pressure  from  the 


FlG-  17.—  A  hand 

01 


24 


FUEL  OIL   AND  STEAM  ENGINEERING 


atmosphere  without.     If  the  barometer  be  at  sea-level  and  the 
temperature  of  the  mercury  column  32°F.,  the  height  of  mercury 


FIG.  18.  —  The  principle  of  the  atmospheric  barometer,  the  condenser  vacuum 
and  the  measurement  of  pressures  above  the  atmosphere. 

will    now  measure    exactly    29.921    inches  for   such   standard 

conditions. 

Vacuum  Pressures.  —  It  has  already  been  pointed  out  that 

measurement  of  pressure  by  means 
of  the  steam  gage  indicates  a  pres- 
sure over  and  above  that  exerted 
by  the  atmosphere  and  conse- 
quently to  ascertain  the  true  ab- 
solute pressure  of  the  fluid  under 
measurement  we  must  add  to  the 
gage  reading  the  atmospheric  pres- 
sure of  the  day.  And  so  in  the 
measuring  of  the  pressure  of  a  con- 
<••  •,.  I  denser,  unavoidably  there  has 

Am          •*-''       H  £rown  up  a  similar  but   opposite 

mw^m^-  Ji          Bit  *  P*^jB    custom  in   which   the   pressure   is 
H(  measured   down  from  the  atmos- 

phere. Such  a  reading  is  known 
as  a  vacuum  pressure.  In  order 
then  to  ascertain  the  absolute 
pressure  P  under  which  a  condenser 
is  operating  it  is  necessary  to  sub- 
tract the  vacuum  pressure  reading 
Pv  from  the  atmospheric  pressure 


FIG.  19.—  Typical  condenser  barom-    rAQr|jno. 
eter  for  steam  turbine  operation.  lnS 

P    =    Pa    ~    PV  (2) 

Thus  if  a  condenser  is  operating  under  28.5  in.  of  vacuum  and 
the  atmospheric  pressure  is  29.92  in.,  we  mean  that  the  actual 
air  and  steam  still  undisposed  of  in  the  condenser  exert  an  abso- 


THEORY  OF  PRESSURES  25 

lute  pressure  equivalent  to  the  difference  between  29. 92  and  28.50 
which  is  1.42  in.  of  mercury. 

Confusion  in  Pressure  Units. — We  now  see  that  readings  in 
inches  of  mercury  for  low  pressure  and  pounds  pressure  per  sq. 
in.  for  high  pressure  are  expressions  that  are  not  at  all  comparable 
to  each  other  and  hence  their  interrelation  becomes  an  endless 
source  of  confusion. 

Relationship  of  Pressure  Units. — By  careful  measurement  of 
the  atmosphere  at  sea-level,  scientists  have  established  that  the 
height  of  a  mercury  column  with  the  mercury  at  32°F.  in  tem- 
perature is  29.921  in.  Such  a  column  of  mercury  one  square  inch 
in  cross-section  weighs  14.696  Ib.  This  gives  us  at  once  a  method 
by  which  we  may  transfer  inches  of  mercury  Im  into  pounds  of 
pressure  per  square  inch  P.  Thus 

/„  =  29.921 
P   "  14.696 

Inches  of  Water  and  Pounds  Pressure  per  Square  Inch. — 
Very  slight  pressures  are  often  measured  in  inches  of  water  above 
or  below  atmospheric  pressures.  Thus,  in  determining  the  draft 
of  a  chimney,  a  "U"  tube  is  inserted  into  the  chimney,  and  the 
height  of  the  unbalanced  portion  of  the  water  column  indicates 
the  draft  in  the  chimney  in  inches  of  water.  Since  a  column  of 
water  1728  in.  high  and  one  square  inch  in  cross-section  at  100°F. 
weighs  exactly  62  Ib.,  the  inches  of  water  lw  may  be  converted 
into  Ib.  pressure  per  sq.  in.  P  by  the  formula 

/„,       1728 
P"    -62- 

The  Thirty  Inch  Vacuum. — In  engineering  practice  a  thirty 
inch  mercury  vacuum  is  considered  to  be  the .  point  of  absolute 
zero  in  pressure.  This  is  not  strictly  true,  however,  for  we  have 
just  seen  that  such  an  absolute  zero  point  is  reached  under  a 
vacuum  pressure  of  29.921  in.  of  mercury.  The  reading  of  the 
column  of  mercury  in  this  case  is  taken  when  the  mercury  is  at 
a  temperature  of  32°F.,  which  is  the  standard  temperature  for 
scientific  measurement.  If,  however,  we  change  our  standard  to 
that  of  58.4°F.  the  same  weight  or  pressure  of  mercury  now  mea- 
sures just  30.0  in.  This  temperature  is  more  nearly  that  of  the 
condenser  room  where  atmospheric  pressures  are  read  and  since 
it  makes  a  column  of  even  thirty  inches  in  height,  we  shall  adopt 
such  a  reading  at  58.4°F.  as  standard  for  absolute  vacuum  meas- 


26 


FUEL  OIL  AND  STEAM  ENGINEERING 


• 


OQ  .Jg 
X 

.  o 

.2  a 

la 


s 


I 
Jl 


.2  o 
H  ^ 


iJ 


1 


e 


II 


THEORY  OF  PRESSURES  27 

urement.     We  shall,  however,  bear  in  mind  that  the  same  col- 
umn at  32°F.  would  stand  at  29.921  in. 

The  Practical  Formula  for  Conversion  of  Pressures. — Since 
we  have  thus  established  an  even  unit  for  the  standard  vacuum, 
we  may  also  consider  14.7  Ib.  pressure  per  sq.  in.  as  its  equivalent 
instead  of  the  cumbersome  figure  of  14.696  as  stated  above.  This 
involves  an  error  of  four  points  in  fifteen  thousand  which  is  negli- 
gible. Our  formula  for  reduction  on  the  thirty  inch  vacuum 
becomes 

Im  30 

~P   ""  147 

To  Reduce  Barometer  Readings  to  the  Standard  Thirty  Inch 
Vacuum. — Although  58.4°  is  nearer  the  condenser  room  tempera- 
ture than  is  the  32°F.  basis,  still  for  accurate  measurement  the 
actual  temperature  of  the  medium  surrounding  the  mercury 
column  should  be  ascertained  and  thus  a  correction  must  be  made 
to  reduce  the  height  of  the  mercury  column  to  what  it  would 
read  if  at  a  temperature  of  58.4°F. 

This  is  best  illustrated  by  taking  a  concrete  example.  Let 
us  suppose  that  the  mercury  column  inserted  into  the  condenser 
of  a  turbine  reads  28.56  in.  when  the  mercury  temperature  is 
82°F.  and  that  a  barometer  in  the  vicinity  indicates  the  atmos- 
pheric pressure  in  the  condenser  room  to  be  30.08  in.  of  mercury 
when  its  mercury  column  is  at  78°F. 

The  first  thing  to  be  done  in  the  solution  of  this  problem  is  to 
ascertain  what  the  two  mercury  columns  would  have  read  had 
their  respective  mercury  columns  been  at  58.4°F.  Scientific 
investigation  indicates  that  the  expansion  of  mercury  is  accord- 
ing to  the  following  equation  in  which  It  is  the  height  in  inches 
of  mercury  at  f  F.  and  Im  at  58.4°F. 

It  =  Im  [1.0026  +  .000104  (t  -  58.4)]  (6) 

Hence,  to  ascertain  the  true  vacuum  reading  in  inches  of  mercury 
we  find  by  substitution 

28.56  =  Im  [1.0026  +  .000104  (82  -  58.4)] 
/./„  =  28.415. 

Similarly  to  compute  the  corrected  barometer  reading  of  the 
day,  we  find  by  substitution  that 

30.08  =  Im  [1.0026  +  .000104  (78  -  58.4)] 
:.Im  =  29.942. 


28  FUEL  OIL  AND  STEAM  ENGINEERING 

The  net  absolute  pressure  will  now  be  the  difference  between 
the  corrected  atmospheric  barometer  reading  and  the  corrected 
vacuum  reading  for  the  condenser,  which  according  to  equation 
(2)  is 

IP  =  29.942  -  28.415  =  1.527  in.  of  mercury. 

Since  all  standard  vacuums  in  engineering  practice  are  now 
measured  on  a  30  in.  vacuum  basis,  we  find  that  the  corrected 
vacuum  reading  Icv  for  a  condenser  is 

Icv  =  30  -  Ip  (7) 

.'.  Icv  =  30  -  1.527  =  28.473  in.  (vacuum). 

This  corrected  vacuum  reading  Icv  which  in  this  case  is  28.473 
is  commonly  spoken  of  as  the  vacuum  referred  to  a  30  in. 
barometer. 

For  delicate  scientific  work  this  reading  should  be  carried  to 
still  further  refinements  by  making  a  correction  for  the  expansion 
of  the  brass  on  the  barometer  scale  and  also  for  a  variation  in 
gravity  at  the  particular  place  of  measurement.  At  high  altitudes 
and  extreme  northern  and  southern  latitudes  such  a  correction  is 
essential. 

Corrections  for  the  Brass  Scale  of  a  Barometer. — Professor 
Marks  in  his  computation  of  steam  tables  for  condenser  work 
published  by  the  Wheeler  Condenser  and  Engineering  Company 
has  ably  discussed  the  correction  for  relative  expansion  of  mer- 
cury and  the  brass  scale  of  the  barometer  as  follows: 

The  linear  expansion  of  brass  is  about  one-tenth  that  of  the 
apparent  linear  expansion  of  mercury  exerting  a  constant  pres- 
sure. Where  a  mercury  column  has  a  brass  scale  extending  its 
whole  height  which  is  free  to  expand  with  changes  in  tempera- 
ture, the  readings  on  the  brass  scale  of  the  height  of  the  mercury 
column  must  be  corrected  for  the  relative  expansion  of  the  mer- 
cury and  the  brass  scale.  The  following  table  is  taken  from  table 
99  of  the  Smithsonian  physical  tables  and  gives  the  constants  for 
various  barometer  heights  by  which  to  multiply  the  temperature 
correction  in  order  to  obtain  the  corrections  of  the  mercury 
column. 

Example. — -Reading  of  barometer  29.84,  temperature  of  baro- 
meter 79°F.  In  the  foregoing  table  the  nearest  figure  to  29.84 
is  29.8  opposite  which  the  correction  factor  is  .0027.  If  it  is  de- 
sired to  reduce  the  barometer  to  a  58.4°F.  standard,  the  change  in 
temperature  is  from  79°  to  58.4°  =  20.6°  and  multiplying  .0027 


THEORY  OF  PRESSURES 


29 


REDUCTION  OF  BAROMETRIC  HEIGHT  TO  STANDARD  TEMPERATURE  CORREC- 
TIONS FOR  RELATIVE  EXPANSION  OF  MERCURY  AND  BRASS  SCALE 


Height  of 
Barometer 
in  inches 

Correction  in 
inches  per 
deg.  F. 

Height  of 
Barometer 
in  inches 

Correction  in 
inches  per 
deg.  F. 

20.0 

0.00181 

28  .'O 

0.00254 

20.5 

0.00185 

28.5 

0.00258 

21.0 

0.00190 

29.0 

0.00263 

21.5 

0.00194 

29.2 

0.00265 

22.0 

0.00199 

29.4 

0.00267 

22.5 

0.00203 

29.6 

0.00268 

23.0 

0.00208 

29.8 

0.00270 

23.5 

0.00212 

30.0 

0.00272 

24.0 

0.00217 

30.2 

0.00274 

24.5 

0.00221 

30.4 

0.00276 

25.0 

0.00226 

30.6 

0.00277 

25.5 

0.00231 

30.8 

0.00279 

26.0 

'      0.00236 

31.0 

0.00281 

26.5 

0.00240 

31.2 

0.00283 

27.0 

0.00245 

31.4 

0.00285 

27.5 

0.00249 

31.6 

0  .  00287 

by  20.6  we  get  .056  in.  as  the  barometer  correction.  Sub- 
tracting this  from  29.84  in.  we  get  the  barometer  reading  for 
mercury  at  58.4°F.  as  29.84  in.  -  .056  in.  =  29.784  in. 

Corrections  for  Altitude  and  Latitude.- — Since  the  height  of  a 
mercury  column  gives  true  pressure  readings  so  long  as  it  repre- 
sents a  definite  force  or  weight  and  since  the  weight  or  force  of 
gravity  varies  at  different  altitudes  and  latitudes  over  the  earth's 
surface,  it  is  necessary  to  enter  such  a  correction  when  the  ex- 
treme refinements  of  the  work  in  hand  demand  it.  The  standard 
value  of  gravity  is  taken  at  32.173.  The  following  formula, 
in  which  Img  is  the  correct  reading,  g  is  the  gravity  coefficient, 
X  the  latitude,  and  h  the  altitude  at  the  point  of  pressure  measure- 
ment, may  be  applied  for  this  correction. 

p32.173  -  .082  Cos  2X  -  .000003/q 
32.173 

Thus  in  a  certain  engineering  investigation  in  Berkeley,  Cali- 
fornia, where  the  latitude  is  38°  and  the  elevation  50  ft.,  the  con- 
denser mercury  column  corrected  for  temperature  read  28. 473  in. 
What  should  its  properly  corrected  reading  be  when  gravity  is 
taken  into  consideration? 


30  FUEL  OIL  AND  STEAM  ENGINEERING 

By  substitution 

32.173  -  .082  X  .2419  -  .00015  . 
Ima  =  32.173 


Such  refinements  as  the  one  for  brass  scale  correction  and  espe- 
cially for  latitude  and  altitude  readjustments  are  not  necessary 
in  most  steam  engineering  tests.  It  is  well,  however,  to  bear  in 
mind  such  computation  in  case  investigations  of  extreme  detail 
should  arise. 


CHAPTER  IV 
MEASUREMENT  OF  TEMPERATURES 


HEN  the  finger  is  inserted  into  a  cup 
of  warm  water  and  then  again  into 
water  formed  by  the  melting  of 
ice  a  distinct  sensation  is  felt  in 
each  case.  Many  years  ago  scien- 
tists and  philosophers  attempted 
to  explain  this  sensation  by  assum- 
ing that  a  substance  existed  which 
they  called  " caloric"  whose  en- 
trance into  our  bodies  caused  the 
sensation  of  warmth  and  whose 
egress  therefrom  gave  the  sensa- 
tion of  cold.  But  heat,  if  a  sub- 
stance at  all,  cannot  be  similar  to 
those  substances  with  which  we  are 
familiar,  since  a  hot  body  weighs 
no  more  than  one  which  is  cold. 

The  discussion  in  this  article 
is  not  concerned  directly  with 
heat  but  rather  with  one  of  its 
effects,  namely,  that  of  change  in 

temperature.  From  the  above  it  is  readily  seen  that  tempera- 
ture is  an  indicator  of  the  physical  effect  of  heat  rather  than  a 
quantitative  means  of  heat  measurement.  This  statement  is 
easily  proved,  for  when  we  place  our  fingers  alternately  upon  a 
piece  of  cold  and  hot  iron  at  the  temperatures  mentioned  for 
water  in  the  opening  paragraph  of  this  discussion,  the  same  phys- 
ical sensation  is  experienced.  Yet  to  transform  the  iron  from  a 
temperature  of  freezing  water  to  that  of  boiling  water  takes  far 
less  heat  than  for  the  transfer  of  water  under  similar  conditions. 
Fixed  Points  for  Thermometer  Calibration. — Since  water  is 
the  most  generally  distributed  substance  through  out  nature  and 
one  of  the  most  convenient  for  handling  in  the  laboratory  its 

31 


FIG.  21. — A  thermocouple  for  high 
temperature  measurement. 


32  FUEL  OIL  AND  STEAM  ENGINEERING 

freezing  point  and  boiling  point  are  used  by  common  consent  as 
two  definite  marks  for  temperature  calibration.  Thus  in  the 
Centigrade  scale  the  freezing  point  of  water  is  the  zero  point  and 
the  boiling  point  of  water  under  standard  conditions  of  atmos- 
pheric pressure  is  the  one  hundred  unit  point.  Again,  in  the 
Fahrenheit  scale  the  freezing  point  of  water  is  the  thirty-second 
division  point  and  the  boiling  point  of  water  the  two  hundred 
and  twelfth  division  point.  Similarly  for  the  Reaumur  scale, 
the  freezing  point  of  water  is  the  zero  division  point  and  the 
boiling  point  of  water,  the  eightieth  division  point. 

The  Various  Temperature  Scales  Employed. — The  Centigrade 
scale  as  described  above  has  grown  into  rapid  use  in  scientific 
investigation  and  now  may  be  said  to  be  universally  adopted 
throughout  the  world  for  such  practice.  The  Fahrenheit  scale, 
on  the  other  hand,  has  so  ingrained  itself  into  engineering  prac- 
tice that  engineers  are  loath  to  part  with  it  in  spite  of  its  cumber- 
some and  unscientific  divisions.  In  this  work,  then,  we  shall  be 
compelled  to  express  temperature  measurement  in  the  Fahren- 
heit scale.  The  Reaumer  scale,  mentioned  above,  finds  slight 
application  in  this  country  and  in  such  places  where  it  is  employed 
it  is  used  for  measurement  in  stills  and  breweries.  All  three  of 
these  scales  are  often  for  scientific  purposes  transformed  to  a 
socalled  absolute  zero  which  is  459. 4°F.  below  the  ordinary  zero 
on  the  Fahrenheit  scale.  A  free  discussion  of  this  absolute  scale 
will  be  set  forth  in  a  discussion  on  thermodynamic  laws  of  gases 
which  will  be  found  in  another  chapter. 

Relationship  of  Fahrenheit  and  Centigrade  Values. — In  order 
that  transfers  from  one  thermometer  scale  to  another  may  be 
conveniently  and  rapidly  accomplished,  it  now  becomes  necessary 
to  develop  some  simple  mathematical  relationships  whereby  this 
may  be  done.  Since  all  of  the  scales  are  graduated  uniformly 
between  the  freezing  and  boiling  point  of  water,  their  relationship 
may  be  said  to  be  linear.  In  the  study  of  analytical  geometry 
we  find  that  such  relationships  may  be  expressed  by  the  straight 
line  formula: 

x  -  X!  =  y  -  yi 
xz-  xl       2/2-  2/i 

wherein  x  and  y  represent  any  simultaneous  temperatures  ex- 
pressed in  different  scale  readings  and  the  subscripts  1  and  2 
represent  definitely  known  points  in  correspondence.  In  order 
then  to  find  a  relationship  between  the  Fahrenheit  and  Centi- 


MEASUREMENT  OF  TEMPERATURES 


33 


FIG.  22.— Oil-fired  Stirling  boilers  at  station  A,  Pacific  Gas  and  Electric  Com- 
pany, San  Francisco. 


34 


FUEL  OIL  AND  STEAM  ENGINEERING 


grade  scale,  if  x  represents  the  Fahrenheit  and  y  the  Centigrade, 
we  find  that  x\  would  be  32  when  y\  is  0,  and  x2  would  be  212  when 
2/2  is  100.  Consequently  we  derive  a  relationship  thus: 

F     -  32         C  -  0 


212  -  32 

77»  Of) 

/*         ~     OZi     == 

.'.F  -  32  = 


100  -  0 


ioo 


(2) 


Y* 

1 


FIG.  23. — The  linear  relationship  of  temperature  scales. 

As  an  example,  if  the  entering  water  in  a  boiler  test  is  84°F., 
this  value  is  converted  at  once  to  the  Centigrade  scale  by  sub- 
stituting in  the  formula 

F-32  =  IC 

or  C  =  ^  (F  -  32)  =  jj  (84  -  32)  =  28.9° 

Relationship  of  Fahrenheit  and  Reaumur  Values. — A  rela- 
tionship between  the  Fahrenheit  and  Reaumur  scales  is  similarly 
established. 


.'.F  -32  = 


(3) 


Thus  in  order  to  illustrate  the  application  of  this  formula  a  tem- 
perature of  84°F.  reduces  to  the  Reaumur  scale  as  follows: 

84  -  32  =  |  JS 
.*.  R  =  23.1° 


MEASUREMENT  OF  TEMPERATURES  35 

Relationship  of  Centigrade  and  Reaumur  Values.  —  To  develop 
a  relationship  between  the  Centigrade  and  Reaumur  scales  the 
same  reasoning  is  involved. 


(4) 


Thus  to  convert  a  Centigrade  reading  of  28.9°  into  the  Reau- 
mur scale,  we  substitute  directly 

R  =  \C 
o 

or  R  =  \  :  X  28.9  =  23.1° 
o 

In  case  that  rapidity  is  necessary  in  the  conversion  of  one  scale 
to  another  and  extreme  accuracy  is  not  required,  a  conversion 
chart  is  easily  constructed  whereby  these  three  scales  may  be 
converted  graphically  from  one  to  the  other. 

Methods  of  Temperature  Measurement.  —  The  ascertaining 
of  correct  temperatures  is  of  extreme  importance.  Due  to  the 
wide  range  of  temperatures  that  occur  in  practice,  a  number  of 
different  methods  of  temperature  measurement  are  necessary. 
The  method  to  be  employed  depends  upon  the  range  of  tempera- 
ture involved  and  often  too  upon  the  accessibility  of  the  ob- 
ject whose  temperature  is  desired.  We  shall  describe  first  the 
approximate  methods  that  are  used  in  the  ascertaining  of 
temperatures. 

Estimation  by  Flame  Color.  —  A  number  of  years  ago  in  the 
steel  industry,  it  was  found  that  a  flame  emitted  definite  grada- 
tions of  color  depending  upon  its  temperature.  In  1905  the 
Bureau  of  Standards  issued  a  bulletin  covering  this  point  and 
made  a  statement  that  one  may  ascertain  temperatures  with  an 
accuracy  of  100  to  150°F.  by  means  of  eye  judgment.  It  is 
stated,  however,  that  it  is  impossible  to  ascertain  temperatures 
above  2200  °F.  As  this  is  the  upper  limit  of  furnace  heating  in 
steam  engineering,  we  need  not  then  be  concerned  with  exceeding 
the  limit. 

In  a  booklet  published  by  the  Halcomb  Steel  Company,  1908, 
the  following  tabulation  is  given  to  aid  eye  judgment  in  esti- 
mating temperatures: 


36 


FUEL  OIL  AND  STEAM  ENGINEERING 


°c. 

°F. 

Colors 

°C. 

°F. 

Colors 

400 
474 
525 
581 
700 
800 
900 

752 

885 
975 
1077 
1292 
1472 
1652 

Red,  visible  in  the  dark  
Red,  visible  in  the  twilight  .  .  . 
Red,  visible  in  the  day-light  .  . 
Red,  visible  in  the  sunlight  .  .  . 
Dark  red  

1000 
1100 
1200 
1300 
1400 
1500 
1600 

1832 
2012 
2192 
2372 
2552 
2732 
2912 

Bright  cherry-red 
Orange-red. 
Orange-yellow. 
Yellow-white. 
White  welding  heat. 
Brilliant  white. 
Dazzling  white, 
(bluish  white). 

Dull  cherry-red  . 

Cherry  red  .  .  .  

The  Melting  Point  of  Metals  and  Alloys. — Another  method  of 
approximately  ascertaining  the  temperature  is  by  means  of  the 
melting  points  of  alloys  and  metals.  A  num- 
ber of  these  alloys  are  on  the  market  and  are 
convenient  in  ascertaining  the  approximate 
temperature  of  furnaces  and  other  heat  gener- 
ating apparatus. 

The  Method  of  Immersion. — A  third 
method  is  by  heating  a  piece  of  metal  of 
known  weight  and  specific  heat  to  the  tem- 
perature of  the  furnace  and  then  immersing 
the  heated  body  in  water.  By  knowing  the 
rise  in  temperature  of  the  water,  the  tem- 
perature of  the  furnace  may  be  approximately 
ascertained.  The  loss  of  heat  in  the  hot  sub- 
stance is  evidently  equal  to  the  heat  gained 
by  the  water.  Let,  tx  be  the  unknown  temperature  of  the  hot 
substance,  Ma  the  weight  of  the  hot  substance  in  lb.,  Mw  the 
weight  of  the  water  in  lb.  U  the  final  temperature  of  the  water, 
h  the  initial  temperature  of  the  water  and  dthe  specific  heat  of  the 
hot  substance;  then,  if  we  assume  that  the  specific  heat  of  the 
water  is  1,  we  may  write  at  once 


300 


FIG.  24. — A   cup   for 
melting  alloys. 


Mx(tx  -  t2)cx  = 
Therefore,  tx  = 


Mxcx 


(5) 


Mean  specific  heats  of  a  number  of  metals  which  may  be  used 
for  this  purpose  are  as  follows: 


MEASUREMENT  OF  TEMPERATURES 


37 


MEAN  SPECIFIC  HEATS 


Substance 
Platinum..  . 
Iron  (cast) . . 
Nickel.. 


Ordinary 

temperature 

0.032 

0.130 

0.109 


Mean  for  high 

temperature 

0.038 

0.180 

0.136 


As  an  example  let  us  suppose  that  4  Ib.  of  cast  iron  heated  to 
an  unknown  temperature  is  plunged  into  20  Ib.  of  water  at  64°F., 
thereby  raising  the  water  to  a  temperature  of  124°F.  By  sub- 
stituting in  the.  formula,  we  have 

••-*&£*+>»  -»»*• 

The  Alcohol  and  Mercurial  Thermometers. — For  accurate 
temperature  readings  up  to  900°F.  the  expansion  of  liquids  is 
made  use  of,  for  experiment  shows  that  the  expansion 
of  a  liquid  is  proportional  to  the  rise  of  tempera- 
ture. Since  alcohol  has  a  low  freezing  point,  in  fact 
so  low  that  it  cannot  be  reached  by  any  natural 
temperature,  the  alcohol  thermometer  is  usually  made 
use  of  for  low  temperature  readings.  Since  its  boiling 
point  is  also  comparatively  low,  it  is  impracticable 
for  high  temperatures.  Mercury,  on  the  other  hand, 
is  an  excellent  substance  to  use  in  thermometers  as 
the  variation  in  its  expansion  coefficient  with  rise  of 
temperature  is  such  that  the  deleterious  effect  of  the 
expansion  coefficient  in  the  glass  tube  is  very  nearly 
offset  by  the  compensating  error  introduced  by  assum- 
ing a  constant  expansion  coefficient  for  the  mercury. 
Mercury  boils  at  676°F.  and  for  many  degrees  below 
this  point  gives  off  considerable  vapor.  As  a 
consequence  the  ordinary  mercurial  thermome- 
ter cannot  be  depended  upon  for  a  higher  tem- 
perature than  500°F.  An  ingenious  device, 
however,  enables  us  to  make  use  of  the  mer- 
curial thermometer  up  to  800  or  900°F.  A 
small  amount  of  nitrogen  gas  is  put  in  the 
upper  column  of  the  thermometer  tube  and  as  the  mercurial 
column  expands  it  consequently  compresses  the  nitrogen  gas. 
The  reactive  pressure  of  the  gas  upon  the  mercury  raises  its  boil- 
ing point  so  that  the  high  temperatures  above  indicated  can  be 
accurately  read. 


FIG.  25. — Hygrome- 
ter for  boiler  room 
humidity. 


38 


FUEL  OIL  AND  STEAM  ENGINEERING 


LI 


The  Expansion  Pyrometer. — For  the  estimating  of  tempera- 
tures higher  than  900°  a  number  of  types  of  instruments  are 
employed.  The  expansion  pyrometer,  which  acts  upon  the  prin- 
ciple that  the  expansion  of  metals  is  proportional  to  the  rise  in 
temperature  may  be  quite  accurately  used  between  the  range  of 
1200  to  1500°F. 

Electrical  Thermometers. — Electrical  thermometers  are,  how- 
ever, the  most  satisfactory  and  accurate  for  steam  engineering 

practice.     Electrical   thermometers 

act  upon  two  distinct  physical 
principles.  One  class  operates  upon 
the  principle  that  the  junction 
point  of  two  metals  when  heated 
generates  an  electromotive  force 
which  is  proportional  to  the  tem- 
perature rise.  Consequently  if  the 
readings  are  made  by  means  of  a 
delicate  galvanometer,  calibrated  to 
read  degrees  Fahrenheit,  an  accu- 
rate type  of  instrument  is  at  once 
evolved.  The  other  principle  is 
based  upon  the  experimental  fact 
that  the  resistance  of  a  metal  varies 
with  the  temperature  rise.  Hence, 
by  measuring  this  rise  in  electrical 
resistance  by  delicately  calibrated 
instruments,  an  accurate  thermome- 
ter results.  The  thermo-couples 
made  use  of  for  the  former  type  of  electrical  thermometer  usually 
consist  of  platinum  with  platinum  alloyed  with  10  per  cent,  of 
rhodium.  In  the  latter  class  the  resistance  element  is  enclosed 
in  a  highly  refractory  substance. 

The  Radiation  Pyrometer. — Where  temperatures  are  above 
the  limit  of  measurement  by  rare  metal  pyrometers,  or  where  the 
point  of  high  temperature  is  inaccessible  to  the  thermo-couple, 
the  radiation  pyrometer  is  employed.  This  instrument  is  fo- 
cused on  the  hot  body  at  a  distance.  The  heat  radiating  from  the 
object  under  investigation  is  reflected  by  a  concave  mirror  in  the 
back  of  the  pyrometer  telescope  and  concentrated  at  a  focus 
point  on  a  small  thermo-couple.  This  thermo-couple  gives  off 
electrical  energy  proportional  to  the  temperature  of  the  radiat- 


FIQ.    26. — Thermo-couple    ready 
for  insertion  in  the  furnace. 


MEASUREMENT  OF  TEMPERATURES 


39 


ing  body,  and  as  a  consequence  the  temperature  is  thus  ascer- 
tained. 

Thus,  the  whole  range  of  temperatures  met  with  in  engineer- 
Pyrometer 


-T 


FIG.  27. — Principle  of  operation  of  the  thermo-couple. 

ing  practice  is  covered  by  some  form  of  accurate  temperature  in- 
dicating device.  The  Bureau  of  Standards  at  Washington  is 
ready  to  calibrate  for  a  small  fee  any  thermometer  sent  to  them. 


FIG.  28. — Galvanometer  for  delicate  temperature  measurement. 

At  least  one  carefully  calibrated  thermometer  should  be  kept  for 
reference  or  comparison  in  the  laboratory  of  any  one  interested  in 
steam  engineering  testing. 


40  FUEL  OIL  AND  STEAM  ENGINEERING 

Standardization  and  Testing  of  Thermometers.— The  testing 
of  thermometers  is  of  utmost  importance.  All  thermometers 
should  be  carefully  calibrated  for  refined  steam^engineering  tests. 
The  Bureau  of  Standards  has  issued  in  its  circular  No.  8,  an  ex- 
cellent guide  for  such  work.  All  thermometers  are  calibrated 
when  completely  immersed  in  the  substance  whose  temperature 
is  being  ascertained. 

The  Stem  Correction. — In  engineering  practice  temperatures 
of  steam  and  water  are  usually  ascertained  by  setting  the  ther- 
mometer into  a  well  which  is  sunk  into  the  pipe  conveying  the 
steam  or  water.  This  well  is  filled  with 
mercury  or  oil  and  the  heat  transferred  to 
the  thermometer  by  conduction.  As  a  con- 
sequence, however,  a  portion  of  the  ther- 
mometer protrudes  in  the  atmosphere  above 
the  well  and  is  consequently  at  a  lower 
temperature.  A  so-called  stem  correction  is 
hence  necessary  to  ascertain  the  correct  read- 
ing of  the  thermometer. 

This  correction  is  large  if  the  number  of 
FIG.  29.— Well  for    degrees  emergent  and  the  difference  of  tem- 
thennometer     inser-    perature   between   the    bath    and  the  space 
above  it  are  large.     It  may  amount  to  more 
than  35°F.  for  measurements  made  with  a  mercurial  thermometer 
at  750°F. 

The  stem  correction  may  be  computed  from  the  following 
formula: 

Stem  correction  =  Kn(t\  —  t%)  (6) 

K  =  factor  for  relative  expansion  of  mercury  in  glass; 
0.00015  to  0.00016  for  Centigrade  thermometers; 
0.000083  to  0.000089  for  Fahrenheit  thermometers,  at  or- 
dinary   temperatures,    depending    upon    the    glass    of 
which  the  stem  is  made. 

n  =*  number  of  degrees  emergent  from  the  bath. 
ti  =  temperature  of  the  bath. 
<2  =  mean  temperature  of  the  emergent  stem. 

Thus  suppose  that  the  observed  temperature  was  100°C.  and  the 
thermometer  was  immersed  to  the  20°  mark  on  the  scale,  so  that 
80°  of  the  mercury  column  projected  out  into  the  air  and  the 


MEASUREMENT  OF  TEMPERATURES  41 

mean  temperature  of  the  emergent  column  was  found  to  be  25°C., 
then 

Stem  Correction  =  0.00015  X  80  X  (100  -  25°) 
=  0.9°. 

As  the  stem  was  at  a  lower  temperature  than  the  bulb,  the 
thermometer  read  too  low,  so  that  this  correction  must  be  added 
to  the  observed  reading  to  find  the  reading  corresponding  to  total 
immersion. 


T 

b 


CHAPTER  V 
THE  ELEMENTARY  LAWS  OF  THERMODYNAMICS 

S  pointed  out  in  the  discussion  on 
temperatures,  scientists  in  former 
times  conceived  that  the  phenomena 
accompanying  the  addition  or  sub- 
traction of  heat  could  only  be  ex- 
plained by  the  existence  of  a  fluid 
which  they  called  "  caloric." 

But  these  scientists  or  calorists, 
as  they  were  called,  had  to  give  a 
hitherto  unknown  property  to  their 
substance  and  maintained  that 

~*—™\ — *•"  -  " caloric"    was    a    weightless    fluid. 

This  substance  also  had  the  prop- 
erty of  filling  the  interstices  of  bodies 
and  of  passing  between  bodies  over 
any  intervening  space.  To  illus- 
trate, they  said,  " caloric"  would 
fill  the  interstices  of  a  body  as 

water  enters  a  sponge.  Now,  when  we  squeeze  a  sponge  some 
of  the  water  oozes  out  and  wets  our  hands.  The  calorists  as- 
sumed that  the  friction  or  rubbing  of  a  body  with  the  hand  for 
instance,  made  the  hand  warm  because  friction  was  supposed 
to  decrease  the  capacity  of  a  body  for  holding  "caloric,"  and  as 
in  the  squeezing  of  the  sponge,  water  oozes  out,  so  caloric  oozed 
out  and  made  the  hand  feel  warm. 

The  Irrefutable  Experiments  of  Davy. — Davy,  however,  ex- 
ploded this  theory  in  1799,  when  by  rubbing  two  pieces  of  ice 
together,  he  actually  caused  the  ice  to  melt.  This  evidently 
would  be  impossible  under  the  caloric  theory  above  stated, 
according  to  which  friction  caused  capacity  for  caloric  to  be  de- 
creased. Yet  here  was  evidenced  the  reverse.  From  time 
immemorial,  men  have  considered  that  the  force  of  truth  is  al- 
mighty, and  yet  how  slow  the  human  race  is  to  overthrow  an 

42 


FIG.  30. — The  establishment  of 
Boyle's  law. 


ELEMENTARY  LAWS  OF  THERMODYNAMICS  43 

imperfect  but  well-established  theory.  For  instance,  so  power- 
ful was  Sir  Isaac  Newton's  grip  on  the  scientific  world  that  be- 
cause he  announced  that  no  successful  correction  could  ever  be 
made  for  the  uneven  refraction  of  light  rays  in  lenses,  the  whole 
world  for  fifty  years  thoroughly  abandoned  the  idea  of  ever  being 
able  to  use  refractive  telescopes,  and  consequently,  during  that 
period  we  find  telescopic  reflective  mirrors  used  entirely. 


FIG.  31. — The  furnace  gases  and  entering  air  obey  rigid  but  simple  thermo- 
dynamic  laws.  (Boiler  fronts  at  Long  Beach  Plant  of  the  Southern  California 
Edison  Company.) 

Joule's  Complete  Demonstration  of  the  Mechanical  Equivalent 
of  Heat. — And  so  it  was  in  the  case  of  the  theory  of  heat.  Not- 
withstanding the  all-powerful  demonstration  of  Davy  in  1799, 
it  remained  for  Joule,  nearly  fifty  years  later  to  finally  put  forth 
the  finishing  data  to  forever  overthrow  the  caloric  theory  and 
introduce  the  modern  idea  of  heat.  This  eminent  scientist 
constructed  a  machine  in  many  respects  similar  to  an  ice-cream 
freezer,  the  essential  difference  being,  however,  that  the  machine 
was  used  to  increase  the  heat  in  the  liquid  instead  of  cooling  the 
same.  Joule  conceived  the  idea  that  heat  was  one  form  of  energy. 
Should  this  be  true,  it  should  be  mutually  convertible.  One  of 
the  easiest  methods  of  measuring  energy  is  the  well  known  pile 
driver.  Energy  is  definitely  computed  by  weighing  the  hammer 
in  pounds  and  multiplying  this  weight  by  the  distance  in  feet 
through  which  the  weight  falls.  The  result  is  foot-pounds  en- 
ergy. By  a  clever  contrivance  constructed  somewhat  on  this 
principle,  Joule  measured  the  amount  of  energy  absorbed  in  his 


44  FUEL  OIL  AND  STEAM  ENGINEERING 

machine  and  the  consequent  rise  of  temperature  in  the  liquid. 
He  soon  established  the  fact  that  a  definite  number  of  foot- 
pounds of  mechanical  energy  was  equivalent  to  a  definite  number 
of  heat  units  in  the  liquid.  This  experimental  result  is  most 
important  and  is  one  of  the  basic  principles  of  modern  engineer- 
ing. Careful  scientific  measurements  have  proved  that  one 
British  thermal  unit,  or  B.t.u.,  of  heat  energy  is  equivalent  to 
777.5  foot-pounds  of  mechanical  energy. 

The  First  Law  of  Thermodynamics. — From  this  discussion 
it  follows  that  the  first  and  greatest  law  of  thermodynamics  is 
the  mathematical  expression  of  the  fact  that  heat  energy  and 
mechanical  energy  are  mutually  interchangeable.  Thus  if 
W  represents  energy  in  foot-pounds;  H,  energy  in  heat,  units; 
and  J,  this  experimentally  determined  constant,  we  have  the 
relationship 

W  =  H  J  (1) 

In  steam  engineering  practice  H  is  usually  expressed  in  B.t.u. 
and  the  quantity  J  has  a  value  of  777.5  as  has  been  stated  above. 
In  other  words,  1  B.t.u.  of  heat  energy  is  equivalent  to  777.5  ft. 
Ib.  of  mechanical  energy.  In  the  chapter  on  units,  we  have  de- 
fined the  fundamental  unit  of  energy,  namely  the  foot-pound. 
This  unit  of  heat  energy  now  introduced,  known  as  the  British 
thermal  unit,  is  the  J-fso^h  part  of  the  heat  necessary  to  raise 
one  pound  of  water  from  32°F.  to  212°F.  under  standard  atmos- 
pheric conditions  of  pressure.  This  is  the  unit  which  has  been 
adopted  by  Marks  and  Davis,  in  their  "Steam  Tables  and  Dia- 
grams" and  although  differing  from  other  previously  existing 
units  is  nevertheless  practically  universally  adopted  at  this  time. 

Boyle's  Law. — Early  in  the  last  century,  Boyle  established  the 
fact  that  a  perfect  gas,  such  as  air,  follows  very  closely  the  law 
known  as  Boyle's  law,  that  the  product  of  its  pressure  and  vol- 
ume is  always  constant  provided  the  temperature  is  kept  constant. 
Expressing  this  in  mathematical  symbols,  if  p  is  the  absolute 
pressure  in  Ib.  per  sq.  ft. ;  v,  the  volume  in  cu.  ft.  occupied  by  1 
Ib.,  we  have  the  relationship 

pv  =  poVQ  (2) 

Steam  is  not  a  perfect  gas  and  hence  does  not  obey  this  law  with 
exactness,  still  the  formula  may  be  used  with  a  fair  degree  of 
accuracy  when  considering  superheated  steam.  Accurate  formu- 
las will  be  given  later  for  steam  variation.  As  an  instance,  how- 


ELEMENTARY  LAWS  OF  THERMODYNAMICS 


45 


ever,  of  approximate  computation,  let  us  consider  a  boiler  oper- 
ating at  186.3  Ib.  gage  or  201  Ib.  absolute  pressure  per  sq.  in., 
and  producing  superheated  steam  at  527°F.  If  we  know  the  vol- 
ume at  one  pressure  we  may  ascertain  approximately  the  volume 
at  another  pressure.  In  the  steam  tables  the  volume  of  steam  at 
201  Ib.  pressure  per  sq.  in.  is  found  to  be  2.83  cu.  ft.  per  Ib.  Hence 

200  ^  2  83 
at  250  Ib.  pressure  the  volume  would  become  v  =   -  '* 


=  2.26  cu.  ft.  per  Ib.  The  steam  tables  give  this  quantity  by 
actual  experiment  as  2.31.  Hence  the  formula  is  seen  to  work 
with  superheated  steam  within  2.5  per  cent,  of  accuracy.  For 
chimney  flue  gases  and  air,  however,  Boyle's  law  is  very  exact. 


FIG.  32.  —  Superheated  steam  approximately  obeys  simple  thermodynamic 
laws.  (Superheated  steam  ducts  of  station  C  of  the  Pacific  Gas  &  Electric 
Company  in  Oakland.) 

Charles'  Law.  —  In  1806  another  law  was  found  connecting  the 
variables  of  a  perfect  gas.  This  great  law,  known  as  Charles' 
Law,  sets  forth  the  fact  that  when  the  pressure  is  kept  constant  the 
volume  of  a  gas  increases  proportionately  to  the  increase  in  tem- 
perature. Thus  if  t  is  the  temperature  in  degrees  Fahrenheit 
this  law  states  that 


As  an  illustration,  if  we  wish  to  compute  the  volume  that  1 
Ib.  of  air  would  occupy  in  a  furnace  at  2100°F.,  knowing  that  VQ 
has  a  value  of  12.39  cu.  ft.  for  air  at  32°F.  then 


v  =   12.39 


=  69-8  cu-  ft- 


46  FUEL  OIL  AND  STEAM  ENGINEERING 

The  Absolute  Scale. — The  establishment  of  this  law  indicates 
the  fact  that  all  temperatures  should  naturally  be  measured  from 
a  point  other  than  that  of  the  freezing  temperature  of  water. 
Thus  it  is  seen  from  the  above  that  a  point  of  459.6°  below  the 
ordinary  Fahrenheit  scale  would  be  known  as  an  absolute  zero. 
Throughout  this  work  then  T  will  represent  the  absolute  scale 
and  t  the  ordinary  scale.  Thus 

T  =  t  +  459.6  (4) 

The  Composite  Law  of  Gases. — Since  it  is  seen  that  the  prod- 
uct of  the  pressure  and  volume  is  proportional  to  the  change  in 
absolute  temperature  we  shall  now  write  one  of  the  most  useful 


FIG.  33. — Saturated  steam  obeys  not  at  all  the  simple  laws  of  thermodynamics. 
(Circulating  water  pumps  operated  by  saturated  steam  at  the  Redondo  plant 
of  the  Southern  California  Edison  Company.) 

formulas  in  the   computation   of   gas   constants,   namely    that 

pv  =  RT  (5) 

in  which  R  is  a  constant. 

In  the  case  of  air,  let  us  see  if  we  can  compute  this  constant. 
Experimentally  it  is  found  that  the  volume  of  air  in  a  boiler  room 
temperature  of  84°F.  is  13.71  cu.  ft.  per  Ib.  when  the  atmospheric 
pressure  is  14.7  Ib.  per  sq.  in.  Substituting  in  the  above  for- 
mula we  have  14.7  X  144  X  13.71  =  R  (459.6  +  84).  There- 
fore R  =  53.3. 

A  Formula  for  Gas  Density. — If  we  let  y  be  the  density  of  a 
gas,  it  is  evident  that  it  has  a  value  equal  to  the  reciprocal  of  v 


ELEMENTARY  LAWS  OF  THERMODYNAMICS  47 

in  the  above  equation.  In  other  words  the  density  of  a  gas  is 
the  weight  of  1  cu.  ft.  under  standard  conditions  of  pressure  and 
temperature.  We  may  then  write  without  further  proof  the 
formula, 

RJ  =-\-  (6) 

To  Compute  "R"  for  Any  Gas. — In  the  measurement  of  gases 
there  is  a  standard  pressure  and  temperature  to  which  all  gas 
volumes  and  densities  are  reduced  in  order  to  have  some  basis 
of  comparison.  These  standard  conditions  are  the  temperature 
of  freezing  water  and  the  pressure  of  the  atmosphere  at  sea-level. 

From  the  equation  last  writen  above,  it  is  now  evident  that  since 
p  and  T  are  constant  for  all  gases  under  this  standardized  method 
of  comparison,  then  the  product  of  R  and  7  must  also  be  constant. 
This  gives  us  a  method  or  rather  formula  by  which  we  may  obtain 
the  value  of  R  for  any  gas  if  we  know  its  density.  The  molec- 
ular weights  of  all  gases  may  be  obtained  by  reference  to  any 
standard  book  on  elementary  chemistry. 

Let  us  multiply  both  sides  of  the  above  equation  by  the  molec- 
ular weight  m  and  by  rearranging  the  terms,  we  have 

pm 
Km  =  — ^r- 


For  oxygen  y   =  0.089222  Ib.  per  cu.  ft.  at  atmospheric  pres- 
sure and  32°F.  and  m  =  32. 

14.7  X   144  X  32 
0.089222  X  49L6" 

Since  this  product  Rm  is  always  a  constant,  we  have  for  any 
perfect  gas  that 


R  =  -  (7) 

m 

This  formula  together  with  the  preceding  general  formulas 
for  pressures  and  volumes  now  enables  us  to  ascertain  practically 
all  the  constants  for  perfect  gases. 

As  an  example  let  us  assume  that  the  temperature  of  an  es- 
caping chimney  gas  is  40,0°F.  What  would  be  the  density  of  the 
nitrogen  content  of  the  escaping  flue  gases?  First  find  the  value 
for  R  for  nitrogen  for  which  m  =  28. 

=  54.98 


48  FUEL  OIL  AND  STEAM  ENGINEERING 

Hence  since 


™    i,         K  14.7X144 

We  have  5 


459+400 
.'.7  =  .04475 

It  is  always  convenient  to  express  volumes  as  the  number  of 
cu.  ft.  per  Ib.  Hence  when  the  symbol  V  is  used  it  will  mean  the 
total  volume  content  of  the  gas  under  consideration.  If  M  repre- 
sents the  weight  of  this  volume  V  we  have  the  relationship 

Mv  =  V  (8) 

or  since  pv  =  R  X  T,  therefore 

pV  =  M  X  RT  (9) 

Thus  if  we  have  given  18.805  Ib.  of  dry  flue  gas  we  can  easily 
compute  the  volume  it  would  occupy  when  leaving  the  chimney 
at  400°F.,  if  it  is  known  that  the  value  of  R  for  the  chimney  gas 
is  51.  4.  Thus 

14.7  X  144F  =  18.805  X  51.4  X  (400  +  459.6) 

:.V  =  393.5  cu.  ft. 

Further  Illustrative  Examples.  —  In  order  to  still  further  illus- 
trate the  wide  uses  to  which  the  formulas  above  given  may  be 
applied  in  engineering  practice,  the  following  six  problems  are 
worked  out  in  full  : 

1.  Find  the  volume  of  one  pound  of  air  in  a  compressor  at  a  pressure  of 
100  Ibs.  square  inch,  the  temperature  being  32°F. 

From  Boyle's  Law  : 

pv  =  p0v0 

at  32°F.,  V0  for  1  Ib.  of  air  is  12.39  cu.  ft.  and  p0  =  14.7  X  144 
14.7X144X12.39 

100X144          =l-82cu.ft.     An.. 

2.  From  Charles'  Law  find  the  volume  of  one  Ib.  of  air  at  atmospheric 
pressure  and  72°F. 


=  12-39  l  +         "  13-4  cu-  ft-  Ans- 


3.  Find  the  temperature  of  two  ounces  of  hydrogen  contained  in  one  gallon 
flask  and  exerting  a  pressure  of  10,000  Ibs.  per  sq.  in. 
2  oz.  =1  gal. 

16  oz.  =  1  Ib.  or  8  gals.  =  1.068  cu.  ft. 
pv     10,000X144X1.068 


.'.T  =  2050°F.  (abs.)    Ans. 
or  t  »  2050  -  459,6  =  1590,4°F.    Ans 


ELEMENTARY  LAWS  OF  THERMODYNAMICS  49 

4.  How  large  a  flask  will  contain  1  Ib.  of  Nitrogen  at  3200  Ibs.  per  sq.  in. 
pressure  and  70 °F.  ? 

p  =  3200  X  144,  T  =  459.6  +  70  =  529.6,  R  =  54.98 

7~>  fjl 

pv  =  RT  v  =--  — 

54.98  X  529.6  ,, 

"V  =  3200X144      °-«*lou.ft.     Ans. 

5.  Ten  Ibs.  of  air  at  200°F.  occupy  120  cu.  ft.     What  must  be  the  pres- 
sure? 

V  =  120 
M  =    10 
R  =  53.33 
T  =  659.6 

MRT      10X53.3X659.6      0_K_ .,  ^ 

.'.p  =     y      =  —         12Q —     -  =  2950  Ib  per  sq.  ft.     Ans. 

6.  How  many  Ibs.  of  air  does  it  take  to  fill  5600  cu.  ft.  at  15  Ibs.  per  sq.  in. 
pressure  and  60°F.? 

pV  =  MRT 
V  =  5600     p  =  15  X  144     R  =  53.3     T  =  459.6  +  60  =  519.6 

15X144X5600 
'  '  M  ~~        53.3X519.6 


CHAPTER  VI 
WATER  AND  STEAM 


S  we  look  about  us  in  nature,  we 
find  that  all  inanimate  creation 
presents  itself  to  us  in  three  dis- 
tinct physical  states.  Certain 
bodies,  for  instance,  of  them- 
selves readily  maintain  their  shape 
while  others,  although  non  variant 
in  density,  nevertheless  seem  to 
have  no  particular  physical  con- 
figuration but  seek,  due  to  the 
force  of  gravitation,  the  lowest 
level  attainable  and  consequently 
must  as  a  rule  be  held  in  a  con- 
taining vessel.  On  the  other  hand, 
a  third  class  of  bodies  is  found  not 
only  possessing  no  particular  phys- 
ical configuration,  but  which  ac- 
tually seem  inherently  desirous  of 
expanding  to  such  an  extent  that 

they  must  as  a  rule  be  completely  housed,  bottom  and  top,  in  a 
containing  vessel. 

In  the  class  room  or  in  the  power  plant,  it  is  easy  to  find  il- 
lustrations of  these  three  general  classifications.  Thus,  chalk, 
iron  pipe,  and  coal  are  instances  of  the  first  division  and  are 
known  as  solids.  Crude  petroleum,  water,  and  kerosene  are 
instances  of  the  second  division,  and  are  called  liquids.  Finally, 
air,  steam,  and  producer  gas  illustrate  the  third  division,  and 
are  called  gases. 

These  States  are  Possible  to  all  Bodies. — The  most  interest- 
ing thing  about  these  socalled  states  of  matter,  and  indeed  the 
item  of  most  importance  to  the  engineer,  is  that  by  varying  the 
pressure  externally  forcing  itself  against  the  sides  of  any  one  of 
these  bodies  and  by  adding  or  subtracting  the  heat  that  may  be 
held  in  store  within  the  body  itself,  any  solid  may  be  converted 
into  a  liquid  and  then  into  a  gas,  or  any  liquid  may  be  converted 

50 


FIG.  34. — Water  and  steam  space 
in  water  tube  boiler. 


WATER  AND  STEAM  51 

into  a  solid  or  a  gas,  or  any  gas  may  be  converted  into  a  liquid 
then  into  a  solid. 

The  Fundamental  Principle  in  Steam  Engineering. — It  is 
this  property  of  matter  that  makes  the  operation  of  the  steam 
engine  possible.  For  if  we  were  not  able  to  heat  water  and  con- 
vert it  into  steam,  it  would  be  impossible  to  make  use  of  this 
liquid  for  steam  engineering  purposes,  although  it  is  the  most 
widely  distributed  in  nature. 

Again,  since  fuel  oil  must  be  converted  into  the  gaseous  state 
before  it  readily  and  efficiently  burns  beneath  the  boiler,  it  would 
certainly  be  cumbersome  and  impractical  for  its  use  in  the  great 
majority  of  central  stations  if  it  could  not  be  conveyed  through 
pipes  or  in  oil  tanks  as  a  liquid  from  the  oil  fields  to  the  place  of 
consumption. 

Steam  Engineering  Still  Supreme. — Since  water  is  so  widely 
disseminated  in  nature  and  since  it  can  be  readily  and  efficiently 
changed  from  one  state  to  another,  it  is  the  working  substance 
that  today  still  drives  the  vast  majority  of  power  developing 
mechanisms  in  the  industries  in  spite  of  the  rise  of  the  gas  engine 
and  the  great  modern  evolution  in  water  power  development. 

Let  us  then  trace  the  physical  phenomena  that  accompany 
the  transformation  of  water  into  the  solid  state  which  of  course 
is  necessary  in  the  production  of  ice,  and  again  from  the  liquid  to 
the  gaseous  state  which  becomes  necessary  in  the  production  of 
steam. 

The  Formation  of  Ice. — Let  us  first  start  with  a  pound  of 
water  at  ordinary  temperatures — say  at  62°F.  As  we  begin  to 
lower  the  temperature,  in  other  words  to  draw  off  heat,  the  vol- 
ume slightly  decreases.  Thus  the  pound  of  water  now  occupies 
less  space  than  formerly.  Hence,  if  this  water  was  on  the  sur- 
face of  a  mountain  lake  and  the  night  was  getting  cooler,  the 
surface  water  would  sink  to  the  lake  bottom  and  allow  warmer 
water  from  the  bottom  to  rise  only  to  be  cooled  at  the  surface 
to  again  drop  to  the  bottom.  This  is  what  is  known  as  water 
circulation  and  is  very  important  in  steam  generation,  as  we  shall 
see  later. 

When,  however,  the  water  under  consideration  lowers  to  a 
temperature  of  39.4°F.,  a  strange  thing  happens.  Something 
develops  in  its  internal  structure  that  now  makes  the  water  ex- 
pand as  the  temperature  is  further  lowered.  A  unit  volume  of, 
water  now  becoming  lighter  than  formerly,  no  longer  will  it 


52  FUEL  OIL  AND  STEAM  ENGINEERING 

sink  to  the  lake  bottom  but  remains  on  the  surface.  Hence 
when  a  short  time  later  the  water  on  the  surface  is  lowered  to 
32°F.  or  freezing  point,  ice  is  formed  on  the  surface  only,  since 
water  is  a  poor  conductor  of  heat.  Nature  thus  protects  the 
fish  in  the  waters  below. 

Coming  back  from  the  mountain  lake,  however,  to  the  forma- 
tion of  ice  in  the  ice  plant  when  the  temperature  has  reached 
32°F.,  although  heat  be  now  driven  off,  the  water  does  not  lower 
itself  in  temperature  but  remains  at  this  temperature  until  it 
has  all  been  converted  into  ice. 

Latent  Heat  of  Fusion. — The  quantity  of  heat  necessary  to 
form  one  pound  of  ice  at  32°F.  from  one  pound  of  water  at  32°F. 
is  a  definite  measurable  quantity  and  is  known  as  the  latent  heat 
of  fusion.  By  careful  measurement,  the  latent  heat  of  fusion  for 
water  has  been  found  to  be  142  B.t.u.  That  is,  to  convert  one 
pound  of  water  at  32°F.  into  ice  at  32°F.  requires  the  drawing  off 
of  as  much  heat  as  would  approximately  be  required  to  lower  one 
pound  of  water  one  hundred  forty-two  degrees  in  temperature. 

When  this  pound  of  water  is  converted  into  ice,  its  volume  still 
further  expands.  Hence,  one  pound  of  ice  will  float  in  water. 
This  accounts,  of  course,  for  the  floating  of  icebergs  on  the  water 
surface,  and  furthermore  this  sudden  increase  in  volume  accounts 
for  the  rutpure  in  pipes  and  other  nuisances  that  occur  in  severely 
cold  weather. 

Going  back  to  our  pound  of  water  now  converted  into  a  pound 
of  ice,  let  us  again  proceed  to  draw  off  heat.  It  is  now  found  that 
we  may  lower  the  temperature  of  the  ice  much  more  easily  than 
when  it  existed  as  a  liquid.  Indeed  only  about  one-half  the  heat 
is  required  to  be  drawn  off  per  degree  lowering  in  temperature 
while  its  volume  practically  remains  constant. 

The  Formation  of  Steam. — Let  us  now  proceed  to  a  considera- 
tion of  the  physical  changes  and  phenomena  that  occur  when 
water  passes  into  steam.  Starting  with  water  at  say  62°F., 
as  we  add  heat  the  temperature  increases  at  the  rate  of  about  1°F. 
for  every  unit  of  heat  energy  added  to  the  water.  At  the  same 
time  the  volume  slightly  increases.  Hence,  if  our  pound  of  water 
under  consideration  be  situated  at  the  bottom  of  the  well-known 
tea-kettle,  the  observation  of  which  led  James  Watt  to  the  inven- 
tion of  the  steam  engine,  this  pound  of  water  becoming  now  less 
dense  will  rise  to  the  top  and  cooler  water  at  the  top  will  sink  to 
the  bottom  which  in  turn  is  passed  again  to  the  top  as  it  becomes 


WATER  AND  STEAM 


53 


heated  to  make  way  for  more  water  from  the  top  to  be  heated 
along  the  portion  exposed  to  the  heat  application.  Thus  the 
water  becomes  warmer  and  warmer  and  the  transference  from 
bottom  to  top  continues.  The  ease  with  which  this  transfer  of 
heated  bodies  of  water  takes  place  has  much  to  do  with  efficient 
operation  of  the  steam  boiler  which  may  be  likened  to  an  enlarged 


£00 


190 


'£00 


f 


HEAT  UNITS  IN     B.TM. 


£00 


4-00 


600 


GOO 


1000         1200 


FIG.  35. — The  temperature  heat  diagram. 

Here  is  graphically  indicated  the  history  of  a  pound  of  water  in  its  relationship  with 
temperature  and  heat.  Beginning  at  32°F.  and  atmospheric  pressure,  by  drawing  off  heat 
the  horizontal  line  ab  is  traced,  showing  that  the  temperature  remains  constant  until  the 
water  is  completely  converted  into  ice,  after  which  the  temperature  rapidly  falls  at  the 
rate  of  about  one  degree  for  every  half  unit  of  heat  drawn  away  By  the  addition  of  heat, 
however,  at  point  a,  the  curve  ae  is  traced,  which  indicates  that  the  temperature  rises  with 
absorption  of  heat  at  the  approximate  rate  of  one  degree  for  each  unit  of  heat  absorbed. 
At  212°F.  and  atmospheric  pressure  the  horizontal  line  eg  is  traced  until  970.4  B.t.u.  are 
absorbed.  After  all  the  water  is  thus  converted  into  steam  the  curve  gh  is  traced  for  super- 
heated steam,  which  rises  at  the  rate  of  about  one  degree  for  every  .47  of  a  B.t.u.  absorbed. 

tea-kettle  with  accessories  and  appurtenances  to  care  for  its 
increased  responsibilities  as  compared  to  tea-kettle  operation. 
Latent  Heat  of  Evaporation.— The  water  in  this  manner  con- 
tinues to  absorb  heat  until  if  under  atmospheric  pressure,  it 
reaches  a  temperature  of  212°F.  At  this  point,  however,  vast 
quantities  of  heat  may  be  added  and  still  the  water  will  remain 
at  this  temperature  although  it  may  now  be  observed  that  steam 


54  FUEL  OIL  AND  STEAM  ENGINEERING 

is  being  formed  which  too,  has  the  same  temperature  as  the 
water.  Not  until  970.4  B.t.u.  or  sufficient  heat  units  to  raise 
ten  pounds  of  water  almost  one  hundred  degrees  in  temperature 
have  been  added  to  the  pound  of  water  at  212°F.  will  the  pound 
of  water  become  entirely  converted  into  steam  at  212°F.  This 
quantity  of  heat  necessary  is  important  in  steam  engineering 
and  is  known  as  the  latent  heat  of  evaporation  for  water  under 
atmospheric  pressure  conditions.  To  be  succinct,  in  steam  en- 
gineering practice  the  quantity  of  heat  necessary  to  convert  one 
pound  of  water  at  a  given  temperature  and  pressure  into  dry 
steam  at  the  same  temperature  and  pressure  is  known  as  the 
latent  heat  of  evaporation  for  that  temperature  and  pressure  and 
is  usually  expressed  by  the  symbol  Lt.  Steam  boilers  seldom  oper- 
ate at  a  pressure  so  low  as  that  of  atmospheric  conditions.  In- 
deed, while  such  a  pressure  is  but  14.7  Ib.  per  sq.  in.,  the  modern 
boiler  in  the  central  station  operates  at  something  like  ten  to 
fifteen  times  this  pressure.  This  fact  materially  complicates 
computation  in  steam  engineering,  for  it  is  found  that  at  pres- 
sures different  than  that  of  standard  atmospheric  conditions  the 
latent  heat  of  evaporation  is  wholly  different.  Indeed,  so  com- 
plex is  this  law  of  variation  that  no  one  as  yet  has  been  able  to 
give  an  exact  formula  for  its  determination,  although  in  subse- 
quent chapters  approximate  equations  will  be  set  forth.  Hence, 
it  has  become  necessary  to  refer  to  carefully  compiled  steam  tables 
for  such  information  and  a  later  chapter  will  set  forth  the  manner 
of  their  use. 

Other  Variations  Occur  With  Changes  of  Pressure. — When 
water  passes  into  steam,  the  volume — say  of  one  pound — vastly 
increases.  At  atmospheric  pressure  the  volume  of  steam  is  about 
sixteen  hundred  times  what  it  was  when  existing  as  water.  At 
other  pressures  the  volume  relationships  will  of  course  be  differ- 
ent. Again  when  the  pressure  increases  at  which  steam  is  formed, 
the  volume  becomes  less  in  proportion.  No  accurate  mathematical 
formula  has  been  found  for  this  relationship  hence  once  again 
must  we  appeal  to  the  steam  tables. 

Data  Easily  Taken  from  Steam  Tables. — By  experiment  it 
has  been  found  that  varying  amounts  of  heat  are  required  to 
raise  water  from  a  particular  initial  temperature  to  the  boiling 
point,  for  the  boiling  point  is  not  reached  until  a  higher  tempera- 
ture is  attained  as  the  pressure  is  increased.  On  the  other  hand, 
less  heat  is  required  to  convert  a  pound  of  water  at  these  higher 


WATER  AND  STEAM  55 

boiling  points  into  steam.  Since  the  volume  and  density  too 
vary  under  varying  pressures,  the  entire  problem  now  becomes  one 
of  picking  the  proper  constants  for  the  particular  temperature 
and  pressure  under  discussion  and  when  one  by  a  little  practice 
can  use  the  steam  tables  with  facility,  it  is  surprising  to  see  how 
simply  and  directly  most  problems  in  steam  computation  may  be 
solved. 

Total  Heat  of  Steam. — Often  in  steam  engineering  practice 
problems  arise  in  which  we  must  express  the  total  heat  of  steam 
quantitatively  represented  in  each  pound  under  consideration. 
It  makes  little  difference  at  what  point  we  begin  to  estimate  such 
heat  relationships,  but  by  common  consent  the  freezing  point  of 
water  has  been  adopted.  Hence,  the  total  heat  of  steam  is  the 
heat  required  to  raise  one  pound  of  water  from  32°F.  to  the  boil- 
ing point  added  to  the  heat  required  to  convert  this  water  into 
steam  at  that  temperature.  If  the  steam  exist  as  superheated 
steam,  there  must  also  be  added  the  heat  required  to  raise  dry 
saturated  steam  to  the  temperature  of  superheat.  The  various 
mathematical  formulas  for  computing  these  numerical  results 
will  be  taken  up  later  in  a  chapter  entitled  Quality  of  Steam. 

At  this  particular  time  we  shall  write  down  the  simplest  of 
these  formulas  as  an  illustration. 

Total  Heat  of  Dry  Saturated  Steam.— The  total  heat  of  dry 
saturated  steam,  written  Ht  for  a  given  temperature  t,  is  the  sum 
of  the  heat  of  liquid  and  latent  heat  of  evaporization  for  that 
temperature. 

Hence  we  may  write  this  important  fundamental  equation 

Ht  =  ht+Lt  (1) 

Thus  the  total  heat  of  steam  at  212°F.  is 

Ht  =  180  +  970.4  =  1150.4  B.t.u. 

Other  Instances  of  Total  Heats. — If,  however,  the  steam  is 
evaporated  from  the  water  and  then  superheated,  that  is,  an 
additional  quantity  of  heat  is  added  after  all  the  water  has  be- 
come steam,  it  will  then  begin  to  rise  in  temperature  and  the 
quantity  of  heat  necessary  for  each  degree  rise  in  temperature  is 
about  one  half  that  required  per  degree  rise  when  it  existed  as 
water.  This  exact  ratio  is  however  quite  variable  and  ranges 
between  .46  and  .60  depending  upon  the  pressure  and  degree  of 
superheat  attained.  Hence  once  again  appears  the  necessity 
of  steam  tables. 


56  FUEL  OIL  AND  STEAM  ENGINEERING 

It  is  now  readily  seen  that  in  general  three  definite  and  distinct 
considerations  present  themselves  in  the  solution  of  problems 
involving  the  computation  of  total  heat.  The  first  instance  is 
one  in  which  the  steam  exists  in  a  dry  state  and  at  the  tempera- 
ture and  pressure  at  which  it  is  generated  from  the  water.  Such 
steam  is  known  as  dry  saturated  steam.  The  second  instance 
is  that  in  which  the  steam  is  not  completely  dry,  but  holds  in  sus- 
pension small  particles  or  globules  of  water,  and  in  this  instance 
the  mixture  is  known  as  wet  steam.  The  third  instance  is  of 
especial  importance  in  modern  central  station  practice  and  in- 
volves what  is  known  as  superheated  steam.  In  this  case  the 
steam  is  first  formed  by  evaporation  from  water  into  dry  satu- 
rated steam,  after  which  it  is  conveyed  through  pipes  that  are 
exposed  to  high  temperatures,  thus  causing  the  temperature  of 
the  steam  to  be  still  further  raised,  although  the  pressure  prac- 
tically remains  constant. 

The  complete  solution  of  these  three  instances  for  computa- 
tion of  total  heats  will  be  found  in  the  chapter  on  Quality  of 
Steam  as  stated  above.  Meanwhile  the  thorough  mastery  of 
the  fundamentals  of  the  physical  properties  of  water  as  herein 
set  forth  will  be  of  vast  assistance  in  a  clear  understanding  of 
this  later  discussion. 

Examples 

1.  The  water  entering  a  feed-water  heater  is  at  a  temperature  of  75°F. 
and  leaves  the  heater  at  190°F.,  what  is  the  heat  absorbed  per  Ib.  of  water? 

From  the  steam  tables  the  heat  of  liquid  at  75°F.  is  43.05  B.t.u.  and  at 
190°F.  it  is  157.91  B.t.u.     Hence  the  heat  absorbed  per  Ib.  of  water  is 
157.91  -  43.05  =  114.86  B.t.u.— Ans. 

2.  Water  enters  a  boiler  at  160°F.  and  is  converted  into  dry  saturated 
steam  at  200  Ib.  pres.  per  sq.  in.  abs.,  what  is  the  total  heat  required  to 
evaporate  each  Ib.  of  steam? 

The  heat  in  the  entering  water  at  160°F.  is  from  the  steam  tables  127.86 
B.t.u.     The  total  heat  of  dry  saturated  steam  at  200  Ib.  pres.  abs.,  is  1198.1 
B.t.u.     Hence  the  actual  heat  necessary  to  evaporate  each  Ib.  of  steam  is 
1198.10  -  127.86  =  1070.24  B.t.u.— Ans. 

3.  If  the  heat  of  liquid  for  boiling  water  at  212°F.  is  180  B.t.u.  and  the 
latent  heat  of  evaporation  is  970.4  B.t.u.,  how  much  heat  is  required  to 
evaporate  a  pound  of  water  from  an  open  water  heater  which  is  receiving  its 
supply  a£  64°F.? 

Each  Ib.  of  water  entering  at  64°F.  has  a  heat  of  liquid  of  32.07  B.t.u. 
Water  evaporating  into  steam  at  212°F.  has  a  heat  of  liquid  of  180  and  a 
latent  heat  of  evaporation  of  970.4  B.t.u.,  making  a  total  heat  of  evaporation 
of  1150.4  B.t.u.  for  every  Ib.  of  water  so  evaporated.  Hence  the  net  heat 
required  is 

1150.40  -  32.07  =  1128.33  B.t.u.— Ans. 


CHAPTER  VII 
THE  STEAM  TABLES 

JT  has  already  been  shown  that  since 
no  simple  mathematical  laws  have 
as  yet  been  devised  to  express  the 
temperature,  pressure,  latent  heat, 
heat  of  liquid  and  other  funda- 
mental properties  of  steam  and 
water  that  are  absolutely  nec- 
essary in  the  solution  of  steam  en- 
gineering problems,  we  must  resort 
to  carefully  compiled  steam  tables. 
Practically  all  the  research  and 
scientific  investigation  along  the 
lines  of  pure  steam  engineering  of 
the  last  half  century  have  been 
devoted  to  the  more  complete 
establishment  of  some  of  the 
fundamental  constants  involved  in 
the  steam  tables. 

The  three  most  important  of  these  are  the  zero  point  of  the 
absolute  temperature  scale,  the  proper  value  for  a  constant  em- 
ployed in  the  conversion  of  mechanical  energy  into  heat  energy, 
and  the  exact  determination  of  the  heat  required  to  evaporate 
one  pound  of  water  from  2 12°F.  into  dry  saturated  steam  at  212°R 
Since  these  values  are  continually  found  by  more  careful  and 
exacting  experimental  work  to  be  slightly  different  than  formerly 
held,  we  find  that  the  steam  tables  of  recent  publication  are  differ- 
ent than  those  of  former  years. 

The  Steam  Tables  as  Adopted  in  this  Discussion. — The 
Steam  Tables  and  Diagrams  as  computed  by  Marks  and  Davis 
and  published  by  Longmans,  Green  &  Company,  are  today 
universally  recognized  and  are  adopted  as  the  standard  com- 
pilation for  the  problems  cited  in  this  discussion. 

In  the  rear  of  these  steam  tables  an  interesting  discussion 
of  the  methods  employed  by  these  investigators  in  arriving  at  the 

57 


FIG.  36. — The  book  of  steam 
tables. 


58  FUEL  OIL  AND  STEAM  ENGINEERING 

three  fundamental  constants  mentioned  above  is  given.  The 
result  of  these  investigations  shows  that  the  absolute  zero  is  to 
betaken  at  —  459. 6°F.,  the  mechanical  equivalent  of  heat  at  777.5, 
and  the  latent  heat  of  steam  at  212°F.  to  be  970.4  B.t.u. 

Recapitulation  of  Fundamental  Evaluations. — These  three 
constants  are  so  important  that  they  should  be  memorized  and 
for  emphasis  let  us  recapitulate  their  exact  interpretation. 

The  absolute  zero  is  now  found  to  be  a  point  situated  at  459.6° 
F.  below  the  zero  point  on  the  Fahrenheit  scale  or  491.6°F.  below 
the  freezing  point  of  water.  At  such  a  temperature  it  is  supposed 
to  be  impossible  to  further  draw  off  heat  from  any  substance 
for  at  this  temperature  the  heat  storage  is  supposed  to  be  abso- 
lutely exhausted. 

The  mechanical  equivalent  of  heat  as  given  above  means  that 
the  energy  represented  by  one  B.t.u.  or  British  thermal  unit 
of  heat  is  equivalent  to  777.5  ft.  Ib.  of  mechanical  energy.  Or 
if  one  pound  of  crude  petroleum  contains  18,500  B.t.u.,  it  pos- 
sesses as  stated  in  a  previous  chapter,  sufficient  energy  to  raise 
a  human  being  weighing  175  Ib.  a  vertical  upward  distance  6f 
over  18  miles. 

The  latent  heat  of  steam  at  212°F.  and  atmospheric  pressure 
means  that  the  quantity  of  heat  necessary  to  evaporate  one  pound 
of  water  at  212°F.  into  dry  saturated  steam  at  212°F.  is  found 
experimentally  to  be  970.4  B.t.u. 

Analysis  of  a  Typical  Page  of  Steam  Tables. — Let  us  now 
proceed  to  analyze  a  page  of  Marks  &  Davis'  steam  tables,  column 
by  column.  The  illustration  as  given  is  found  on  page  12  of 
this  compilation  and  we  shall  follow  across  the  page  the  line 
corresponding  to  a  temperature  of  231°F. 

Temperatures  in  Fahrenheit  Units. — Since  all  steam  engineering 
computation  is  based  on  temperatures  represented  in  the  Fahren- 
heit scale  instead  of  the  Centigrade  system,  the  temperatures  are 
here  listed  in  the  Fahrenheit  units. 

Pressures  in  Absolute  Notation. — This  column  means  that  the 
pressures  here  given  represent  the  pressure  in  pounds  per  sq.  in.  at 
which  water  will  boil  when  the  temperature  is  that  as  listed  in  the 
first  column.  Further  on  in  the  steam  tables  an  exactly  similar 
table  may  be  found  to  the  one  cited  except  in  this  latter  instance 
the  pressures  are  made  to  vary  pound  by  pound  and  the  corre- 
sponding boiling  temperature  of  water  given. 

In  this  instance,  then,  we  read  that  a  pressure  of  21.16  Ib. 


THE  STEAM  TABLES 


59 


per  sq.  in.  will  be  produced  before  the  water  boils  or  the  formation 
of  steam  begins  at  231°F.  This  pressure,  by  the  way,  is  in  ab- 
solute units  and  would  not  be  the  pressure  read  on  the  steam  gage 
of  a  boiler  room.  Since  the  steam  gage  indicates  pressures  above 


Table  1 :  Temperatures 


Temp. 

Pressure 

W: 

Density 
Ibs  per 

Fahr. 

Its. 

Atrnos' 

per  Ib. 

cu.   ft. 

t 

p 

— 

vor  s 

i/v 

230° 

20.77 

1.413 

19.39 

0.0516 

231 

21.16 

1.440 

19.05 

0.0525 

232 

21.56 

1.467 

18.72 

0.0534 

233 

21.% 

1.494 

18.40 

0.0543 

234 

22.37 

1.522 

18.09 

0.0553 

235° 

22.79 

1.550 

17.78 

0.0562 

236 

23.21 

1.579 

17.47 

0.0572 

237 

23.64 

1.609 

17.17 

0.0582 

238 

24.08 

1.638 

16.88 

0.0592 

239 

24.52 

1.668 

16.60 

0.0602 

240° 

24.97 

1.699 

16.32 

0.0613 

241 

25.42 

1.730 

16.05 

0.0623 

242 

25.88 

1.761 

15.78 

0.0634 

243 

26.35 

1.793 

15.52 

0.0644' 

244 

26.83 

1.826 

15.26 

0.0655 

Heat  Latent    Total 

of  the  heat  of  heat  of 

liquid  evap.    steam 

horq  Lorr;      H 

198.2  958.7  1156.9 

199.2  958.1  1157.2 

200.2  957.4  1157.6 

201.2  956.7  1158.0 

202.2.  956.1  1158.3 

203.2  955.4' 1158.7 

204.2  954.8  1159.0 

205.3  954.1  1159.4 
206.3  953.4  1159.7 
207.3  952.8  1160.0 

208.3  952.1  1160.4 

209.3  951.4  1160.7 

210.3  950.7  1161.1 

211.4  950.1  1161.4 
212.4  949.4  1161.8 


Internal  Energy 

8.  t.  u. 

Evap.  Steam 

lor?  E 

884.3  1082.4 

883.6  1082.7 

882.8  1083.0 

882.1  1083.2 

881.3  1083.5 

880.6  1083.8 

879.8  1084.0 

879.1  1084.3 

878.3  1084.5 

877.6  1084.8 

876.8  1085.0 

876.1  1085.3 

875.3  1085.6 

874.6  1085.8 

873.8  1086.1 


Entropy 


Water     Evap.  Steam 
nor*  L/Torr/T  Nor* 

0.3384- 1.3905  1.7289 

0.3399  1.3875  1.7274 

0.3414  1.3844  1.7258 

0.3429  1.3814  1.7243 

0.3443  1.3784  1.7227 

0.3458 '1.3754  1.7212 

0.3472  1.3725  1.7197 

0.3487  1.3695  1.7182 

0.3501  1.3666  1.7167 

0.3516  1.3636  1.7152 

0.3531  1.3607  1.7138 

0.3546  1.3578  1.7124 

0.3560  1.3550  1.7110 

0.3575  1.3521  1.70% 

0.3589  1.3493  1.7082 


233 
234 


236 
237 
238 
239 

240° 
241 
242 
243 
244 


FIG.  37. — A  typical  page  from  the  steam  tables. 

the  atmosphere,  one  must  subtract  from  this  reading  in  the  steam 
tables  the  atmospheric  pressure  of  the  day  in  order  to  find  the 
proper  gage  pressure.  Thus,  in  this  instance,  if  the  atmospheric 


1010 
C 


uoo 


\ 


FIG.  38. — Marks  &  Davis  method  of  collating  data  for  specific  heat  of  water 
from  three  noted  investigators. 

pressure  of  the  day  be  14.7  Ib.  per  sq.  in.,  a  steam  gage  in  a  boiler 
room  would  read  6.46  Ib.  per  sq.  in.,  when  the  water  in  the  boiler 
is  231°F. 


60  FUEL  OIL  AND  STEAM  ENGINEERING 

This  precaution  is  most  important  and  the  student  should 
carefully  reread  the  former  chapter  on  pressures  if  he  does  not 
thoroughly  understand  the  conversion  of  gage  pressures,  inches 
of  vacuum,  inches  of  mercury,  etc.,  into  standard  absolute  pres- 
sure units. 

Pressures  in  Atmospheres. — In  many  engineering  computations 
pressures  are  given  as  so  many  atmospheres  instead  of  pounds  per 
square  inch.  The  pressure  of  the  standard  atmosphere  is  usually 
taken  as  14.7  Ib.  per  sq.  in.  but  for  very  exact  work  it  is  more 
accurately  14.696  Ib.  per  sq.  in.  Hence  this  column  is  computed 
by  dividing  each  item  in  the  preceding  column  by  14.696,  which 
in  this  instance  is  found  to  be  1.440  atmospheres. 

When,  however,  the  reading  is  below  that  of  ordinary  atmos- 
pheric pressure,  such  values  are  often  desired  in  inches  of  mercury 
since  vacuum  pressures  for  the  condenser  are  given  in  such  units. 
This  particular  column  is  therefore  found  by  dividing  the  corre- 
sponding line  in  the  preceding  pressure  column  by  the  number  of 
inches  of  mercury  equivalent  to  one  pound  pressure  per  square 
inch.  It  is  to  be  remembered  that  this  does  not  even  yet  give  the 
reading  in  inches  of  vacuum.  Pressures  in  absolute  inches  of 
mercury  and  inches  of  vacuum  cause  seemingly  endless  confusion. 
A  complete  discussion  of  this  feature  was  taken  up  under  the 
chapter  on  pressures  and  its  careful  review  is  emphatically  recom- 
mended if  any  unsettled  question  still  exists  in  the  mind  of  the 
reader. 

Specific  Volume. — The  cubic  feet  occupied  by  one  pound  of 
dry  saturated  steam  at  a  given  temperature  and  pressure  is 
known  as  the  specific  volume  of  the  steam  for  that  temperature 
and  pressure. 

This  is  a  factor  often  necessary  in  steam  engineering  compu- 
tations. Yet  no  known  means  has  ever  been  invented  whereby 
this  factor  can  be  accurately  ascertained  by  experiment.  The 
task  is  indeed  one  that  involves  such  difficulties  as  to  make  its 
determination  by  experiment  practically  impossible.  The  sci- 
ence of  higher  mathematics  has  come  to  the  rescue  and  here  is 
indeed  an  instance  where  purely  theoretical  deductions  have 
brought  about  a  practical  solution  of  an  otherwise  unsolvable 
problem  in  steam  engineering. 

This  relationship  involves  the  latent  heat  of  evaporation  L; 
the  absolute  temperature  T  at  which  the  saturated  steam  is 
formed ;  the  ratio  of  the  increase  in  pressure  Ap  to  the  increase  in 


THE  STEAM  TABLES  61 

temperature  At  of  boiling  points  taken  immediately  below  the 
temperature  under  consideration  and  immediately  above  it; 
the  specific  volume  of  the  steam  v  that  is  found,  which  of  course, 
is  the  unknown  value  we  are  desirous  of  computing;  and  the 
specific  volume  of  a  space  occupied  by  one  pound  of  water  vi 
immediately  before  its  conversion  into  steam.  Algebraically  the 
relationship  is  expressed  thus: 

'  -  »i)  (1) 

From  the  steam  tables  we  will  take  our  values  for  Ap  and  At 
immediately  below  corresponding  to  230°F.  and  immediately 
above  corresponding  to  232°F.  Hence 

At  =  (232  -  230)  =  2. 

Ap  =  (21.56  -  20.77)144  =  0.79  X  144  =  114. 
T  =  231  •+  459.6  =  690.6. 
L  =  958.1  X  777.5. 
Vi  =  .016  cu.  ft, 

Substituting,  we  have 

958.1  X  777.5  =  690.6  (~\  (v  -  .016) 

.'.v  =  18.98 

The  value  in  the  table  is  19.05  which  is  seen  to  be  about  one- 
third  of  one  per  cent,  in  error.  This  difference  is  probably  due 
to  the  fact  that  decimals  neglected  in  computation  were  made  use 
of  by  the  comp  ler  of  the  steam  tables,  and  then  too  the  small 
pressure  and  temperature  variations  were  probably  taken  nearer 
together  than  is  possible  in  the  data  actually  set  forth  in  the 
steam  tables. 

Specific  Density. — The  weight  in  fractions  of  a  pound  of  one 
cubic  foot  of  dry  saturated  steam  is  known  as  its  specific  density. 

It  is  evident  that  if  one  pound  of  steam  occupies  19.05  cu.  ft. 
as  taken  from  the  previous  column,  then  1  cu.  ft.  of  steam  would 
weight  1/19.05  of  a  pound  which  is  0.0525  Ib.  Hence  this  col- 
umn is  computed  in  each  case  by  taking  the  reciprocal  of  the 
data  given  in  the  preceding  column. 

The  Heat  of  Liquid. — This  is  one  of  the  most  important  col- 
umns necessary  in  steam  engineering  practice.  Since  the  heat 
of  liquid  technically  means  the  quantity  of  heat  necessary  to 
raise  one  pound  of  water  from  32°F.  to  the  temperature  under 


62 


FUEL  OIL  AND  STEAM  ENGINEERING 


consideration,  it  is  evident  that  by  experimental  data  as  given  in 
this  column  it  has  been  found  that  to  raise  one  pound  of  water 
from  32°F.  to  231°F.,  199.1  B.t.u.  are  necessary  to  be  applied 
from  an  outside  source. 


FIG.  39. — Determination  of  the  specific  heat  of  superheated  steam  from  in- 
vestigations of  Knoblauch. 

The  Latent  Heat  of  Evaporation. — Data  for  the  latent  heat  of 
evaporation  has  been  determined  by  careful  experimental  means. 
It  is  by  definition  the  quantity  of  heat  necessary  to  convert  one 
pound  of  water  at  the  temperature  and  pressure  indicated  into 
dry  saturated  steam  at  the  same  temperature  and  pressure. 
In  this  instance  it  is  seen  that  to  convert  one  pound  of  water  at 
231°F.  into  dry  saturated  steam  at  231°P.,  958.1  B.t.u.  are  nec- 
essary to  be  applied  from  an  outside  source. 


THE  STEAM  TABLES  63 

Total  Heat  of  Dry  Saturated  Steam. — The  total  quantity  of 
heat  required  to  raise  the  temperature  of  one  pound  of  water  at 
32°F.  to  the  temperature  at  which  dry  saturated  steam  may  exist 
under  the  pressure  exerted  in  the  particular  instance,  added  to 
the  quantity  of  heat  then  necessary  to  convert  this  water  com- 
pletely into  dry  saturated  steam  is  known  as  the  total  heat  of 
dry  saturated  steam.  Numerically  speaking,  it  is  seen  that  this 
column  is  at  once  obtained  by  adding  the  heat  of  liquid  and  the 
latent  heat  of  evaporation.  In  a  word,  this  column  is  the  sum  of 
the  two  preceding  columns.  Thus 

#231    =    ^231   -\~L  231  (2) 

/.#23i  =  199.1  +  958.1  =  1157.2. 

Internal  and  External  Work. — One  wonders  where  the  heat 
disappears  when  it  is  being  continually  applied  to  water  at  the 
boiling  point  and  yet  the  temperature  of  the  water  or  steam  does 
not  increase. 

Upon  careful  investigation  it  is  found  that  it  disappears  first 
in  an  internal  absorption  due  to  intermolecular  rearrangement  as 
water  passes  into  steam  which  thereby  stores  up  a  considerable 
quantity  of  energy  to  be  given  out  again  when  the  steam  is  con- 
densed back  into  water.  The  energy  that  disappears  in  this  man- 
ner is  known  as  energy  necessary  to  perform  internal  work. 

On  the  other  hand  in  the  generation  of  steam  from  water  the 
volume  is  vastly  increased.  The  pushing  back  against  external 
pressure  to  make  room  for  such  an  increased  volume  performs 
external  work.  So  that  the  energy  applied  in  steam  generation 
which  goes  toward  latent  heat  of  evaporation  may  be  divided 
into  two  classifications,  known  as  external  and  internal  work. 

No  one  has  as  yet  found  a  method  of  directly  measuring  in- 
ternal work.  We  may,  however,  measure  external  work  or 
even  compute  it  and  then  by  subtraction  from  total  energy  ab- 
sorbed arrive  at  a  value  for  internal  work. 

In  a  former  chapter  on  gases  it  was  shown  that  the  external 
work  accomplished  by  a  gas  expanding  under  constant  tempera- 
ture and  pressure  is  computed  universally  by  subtracting  the 
initial  volume  from  the  final  volume  and  then  multiplying  this 
result  by  the  pressure.  Thus 

External  Work  =  p  (v  —  Vi) 
To  convert  this  into  B.t.u.,  we  have 

External  Work   ..  V-'-  (3) 


64  FUEL  OIL  AND  STEAM  ENGINEERING 

From  the  tables  it  is  seen  that  in  this  instance  p  =  21.16  X  144, 
v  =  19.05,^!  =  .016. 

.'.External  Work  =  21.16  X  144  (19.05  -  .016)  =  74.6  B.t.u. 
/.Internal  Work  =  958.1  -  74.6  =  883.5  B.t.u. 

Entropy  of  Water.  —  In  certain  advanced  problems  in  steam 
engineering,  engineers  and  physicists  have  found  it  convenient 
to  invent  fictitious  qualitites  of  steam.  While  many  have  en- 
deavored to  give  a  physical  interpretation  of  entropy,  perhaps 
it  is  clearer  for  the  student  to  consider  it  as  merely  a  mathemati- 
cal fiction  which,  however,  often  becomes  extremely  useful  for 
the  representation  of  steam  engineering  problems  and  indeed 
assists  wonderfully  in  their  solution. 

On  this  assumption,  entropy  may  be  defined  as  such  a  quantity 
that  when  plotted  against  absolute  temperatures  the  area  under 
the  curve  connecting  all  such  points  will  numerically  represent 
the  amount  of  heat  supplied  to  one  pound  of  matter  in  order  to 
accomplish  the  indicated  change  in  temperature.  Thus  in  the 
instance  at  hand  if  one  should  plot  a  curve  with  ordinates  repre- 
senting absolute  temperatures  and  with  abscissas  representing 
the  entropy  for  each  corresponding  temperature,  the  area  under 
this  curve  would  be  exactly  199.1  units.  For  it  takes  199.1 
units  of  heat  energy  to  raise  one  pound  of  water  from  32°F.  to 
231°F  .or  on  the  absolute  scale  from  491.6°F.  to  690.6°F. 

By  analysis  in  higher  mathematics  it  is  found  that  entropy  of 
water  may  be  quite  closely  computed  by  the  formula 

«-  log.!*-  (4) 

-t   1 

Wherein  6  is  the  entropy  of  water,  Tz  the  absolute  temperature 

at  the  end  of  the  heat  application  and  Ti,  the  absolute  tempera- 

ture at  the  beginning  which  is  usually  taken  at  the  melting  point 

of  ice  or  491.  6°F.  on  the  absolute  scale.     Thus  in  this  instance 

,      T2  231  +  459.6 

=     10g,r-= 

=  2.306  lolo--  =  .  3399. 


The  values  in  the  steam  tables  were  arrived  at  by  a  slightly 
more  accurate  process  than  this  by  taking  into  account  the  fact 
that  the  specific  heat  of  water  is  not  constant  as  heat  is  added. 

The  Entropy  of  Evaporation.  —  Since  the  temperature  remains 
constant  during  the  evaporation  of  water  into  dry  saturated 


THE  STEAM  TABLES 


65 


steam,  it  is  evident  that  the  entropy  curve  in  this  case  would 
simply  be  a  rectangle  as  shown  in  the  illustration  wherein  one 
dimension  is  of  length  T  and  the  area  swept  off  is  of  L  units. 
Hence,  the  entropy  for  heat  of  evaporation  is  evidently 


Entropy  of  evaporation  = 


(5) 


or  in  this  instance, 


958.1 


Entropy  of  evaporation  =  —      ~T^~n  =  1.3875 

Zol  ~r~  4oy.o 


600 
A 


zoo 


^res 


z   f  *        6 

FIG.  40. — The  temperature  entropy  diagram. 


7565 


By  the  invention  of  a  fictitipus  quality  of  water  and  steam,  known  as  entropy,  the  plot- 
ting of  a  diagram  is  made  possible,  so  that  an  area  represents  heat  added.  Thus,  in  the  dia- 
gram above,  the  abscissas  are  entropy  and  the  ordinates  absolute  temperatures.  The  area 
obcf  is  exactly  180  units,  which  is  the  heat  required  to  raise  water  from  32°F.  to  212°F. 
Similarly,  the  area  fcde  is  970.4  units,  which  is  the  heat  required  to  evaporate  one  pound  of 
water  at  212°F.  into  steam  at  212°F. 

Total  Entropy. — The  sum  of  the  entropy  value  for  water  and 
for  heat  of  evaporation  is  called  the  total  entropy  of  dry  saturated 
steam.  This  is  evidently  arrived  at  numerically  by  adding 
together  the  two  preceding  columns.  Thus,  total  entropy  =  en- 
tropy of  water  +  .entropy  of  evaporation 

/  .Total  entropy  =  0.3399  +  1.3875  =  1.7274  (6) 

Tables  for  Superheated  Steam. — In  later  pages  of  the  steam 
tables  are  to  be  found  data  relative  to  superheated  steam.  As  a 
subsequent  chapter  will  deal  largely  with  superheated  steam 
computations,  we  shall  delay  the  consideration  of  superheated 
steam  tables  until  the  reader  has  been  more  thoroughly  grounded 
in  other  fundamental  computations  of  dry  saturated  steam. 


CHAPTER  VIII 
HOW  TO  COMPUTE  BOILER  HORSEPOWER 

HAT  energy  is  never  created  or 
destroyed  is  a  fundamental  postu- 
late of  modern  engineering  prac- 
tice. All  of  our  machines  and 
driving  mechanisms  are,  then, 
simply  devices  by  means  of  which 
we  may  convert  one  form  of  energy 
into  another  form  to  suit  our  con- 
venience or  meet  the  demands  of 
industrial  activity.  Thus  an  elec- 
tric generator  does  not  create 
energy  but  is  merely  a  device 
whereby  energy  existing  in  the 
waterfall  or  in  the  steam  turbine 
may  be  converted  into  electrical 
energy.  Neither  does  the  energy 
James  Watt  ex^s^  inherently  in  the  waterfall, 

have    standardized   a    me-     but    due    to    the    emission    of    heat 
the  Pan-     frQm    the    su^   ^  water   hag    firgt 

been  drawn  from  the  ocean  into 
the  clouds  to  be  later  deposited  on  the  lofty  mountain  peaks. 
Due  to  this  superior  position  it  is  enabled  to  develop  water 
power  energy  and  thus  transfer  the  energy  of  the  sun's  rays  into 
more  useful  form  to  ease  man's  burdens.  And  so  with  the 
steam  boiler,  we  have  fundamentally  a  mechanism  by  which  en- 
ergy latent  in  fuel  oil  or  other  combustible  is  first  given  out  as 
heat  energy  of  combustion  to  be  immediately  converted  into 
latent  heat  energy  of  steam. 

The  Meaning  of  the  Word  "Rating."— The  rapidity  with 
which  this  conversion  of  one  form  of  energy  into  another  form 
may  be  accomplished  is  known  as  the  rating  of  the  mechanism 
involved.  Thus  a  small  boy  may  by  means  of  a  block  and  tackle 
hoist  a  huge  weight  to  the  top  of  a  modern  sky-scraper  and  at  a 
later  observation  one  may  see  a  team  of  horses  straining  to  their 

66 


HOW  TO  COMPUTE  BOILER  HORSEPOWER 


67 


utmost  to  accomplish  the  same  task.  By  close  inspection,  how- 
ever, it  will  be  found  that  the  small  boy  has  by  means  of  inter- 
vening pulleys  been  able  to  take  from  thirty  to  forty  times  longer 
to  accomplish  what  the  horses  did  in  a  comparatively  short  time. 
Hence  power,  the  basis  of  comparative  effort,  is  the  time  rate  of 
doing  work. 

The   Development  of  the   Word   "Horsepower."— After  his 
invention  of  the   steam  engine,   James  Watt  soon  found  that 


FIG.  42. — A  close  up  view  of  the  filling  pipes  for  the  oil  storage  reservoirs  of 
the  Southern  California  Edison  Company's  Long  Beach  Plant.  These  valves 
are  under  control  of  the  oil  company  from  whom  the  oil  is  purchased. 

he  must  devise  some  unit  or  measuring  stick,  as  it  were,  with 
which  to  measure  the  power  of  his  mechanism.  As  he  was  a 
pioneer  in  the  art,  he  had  to  cast  about  for  some  convenient  unit 
to  adopt.  What  more  natural  unit  should  he  consider  than  that 
of  the  draft  horse?  After  watching  a  horse  drawing  up  large 
cakes  of  ice  into  an  ice  house  by  the  use  of  a  snatch  block,  it 
occurred  to  him  that  when  the  horse  pulled  up  a  fairly  good  load 
he  must  be  doing  a  certain  amount  of  work.  After  making 
several  experiments  he  found  that  by  adding  more  sheaves  to 


68  FUEL  OIL  AND  STEAM  ENGINEERING 

the  blocks  the  horse  could  raise  a  greater  load  but  it  took  more 
time  to  do  it.  He  found  that  the  average  dray  horse  was  able 
to  raise  a  load  of  550  Ibs.  at  the  rate  of  60  ft.  per  minute,  or  to  do 
33,000  ft.  Ibs.  of  work  per  minute.  This  unit  Watt  called  a  horse- 
power and  applied  it  to  the  measurement  of  the  power  of  his 
steam  engines. 

The  Boiler  Horsepower. — In  the  early  days  of  the  steam  engine 
the  principle  of  the  conservation  of  energy  had  not  been  firmly 
established.  Indeed  that  heat  was  a  form  of  energy  at  all  was 
a  debated  question  for  many  years  after  the  steam  engine  became 
of  vast  practical  importance. 


FIG.  43. — Steam   flow  meter,  recording  pressure  gage  and  indicating  pressure 
gage,  Station  C,  Pacific  Gas  and  Electric  Company,  Oakland,  California. 

Hence,  since  the  energy  latent  in  steam  was  not  then  known  to 
be  the  underlying  reason  for  the  power  driving  action  of  the  steam 
engine,  the  first  rating  of  the  boiler  was  made  on  the  basis  of 
power  development  in  the  engine  which  received  its  supply  of 
steam  from  the  boiler  in  question.  Thus  a  boiler  that  could 
supply  steam  to  operate  a  steam  engine  developing  50  indicated 
h.p.  was  said  to  be  a  50  h.p.  boiler.  Later  it  became  evident, 
due  to  the  rapidly  increasing  efficiencies  of  the  steam  engine  that 
such  a  rating  was  wholly  variable.  It  was  found,  however,  that 
under  ordinary  working  conditions  a  boiler  which  could  evaporate 


HOW  TO  COMPUTE  BOILER  HORSEPOWER 


THE  MECHANICAL  HORSEPOWER 

FIG.  44. — The  unit  of  power  in  modern  steam  engineering. 


THE  KILOWATT 

FIG.  45. — The  unit  of  power  in  electrical  engineering,  which  is  1.34  times  the 
mechanical  horsepower. 


THE  BOILER  HORSEPOWER 

FIG.  40. — The  unit  of  power  in  boiler  practice,  which  is  13.14  times  the  me- 
chanical horsepower. 


THE  MYRIAWATT 

FIG.  47. — The  unit  of  boiler  rating  proposed  by  certain  national  engineering 
societies,  which  is  13.4  times  the  mechanical  horsepower. 


70  FUEL  OIL  AND  STEAM  ENGINEERING 

30  Ib.  of  steam  per  hr.  at  70  Ib.  pressure  and  taking  feed  water 
at  100°F.  could  usually  operate  a  1  h.p.  engine,  consequently 
this  mode  of  boiler  rating  became  popular. 

In  1884,  the  American  Society  of  Mechanical  Engineers 
adopted  the  following  definition  for  the^boiler  h.p.:  That  a 
boiler  evaporating  34.5  Ib.  of  water  at  212°F.  into  steam  at  212°F. 
per  hr.  should  be  known  as  a  1  h.p.  boiler. 

The  Conversion  of  Boiler  Horsepower  to  Mechanical  Horse- 
power Units. — In  later  years  the  principle  of  the  conservation  of 
energy  finally  became  well  established  and  when  engineers  began 
to  compute  the  actual  energy  represented  in  a  mechanical  horse- 
power as  originally  adopted  by  James  Watt  and  then  compare 
this  to  the  energy  represented  in  the  steam  generated  by  what  was 
known  as  a  one  horsepower  boiler,  it  was  found  that  the  boiler 
horsepower  represented  the  conversion  in  unit  time  of  over  thir- 
teen times  the  energy  represented  in  the  mechanical  horsepower 
unit  acting  over  the  same  unit  of  time. 

It  is  instructive  to  follow  this  computation  as  it  will  familiarize 
the  reader  with  these  two  distinct  units.  Let  us  then  proceed 
to  an  analysis.  The  mechanical  horsepower  unit  is  defined  as  a 
performance  of  work  or  conversion  of  energy  at  the  rate  of  33,000 
ft.  Ib.  per  minute.  Since  1  B.t.u.  of  energy  has  been  found  to 
have  its  equivalent  in  777.5  ft.  Ibs  .of  mechanical  work,  it  is  seen 
that  33,000  ft.  Ib.  of  work  per  minute,  or  1,980,000  ft.  Ib.  of  work 
per  hr.  may  be  represented  by  2547  B.t.u.  per  hr.  From  the 
definition  of  the  boiler  horsepower  above  mentioned,  as  that 
adopted  by  the  American  Society  of  Mechanical  Engineers,  it  is 
seen  that  since  it  requires  970.4  B.t.u.  to  evaporate  1  Ib.  of  water 
at  212°F.  into  steam  at  212°F.,  one  boiler  horsepower  represents 
34.5  X  970.4  B.t.u.  per  hr.  or  33,479  B.t.u.  of  heat  energy  per 
hr.  Hence,  when  we  compare  the  boiler  horsepower  with  the 
ordinary  horsepower  it  is  seen  that  the  boiler  horsepower  repre- 
sents a  unit  which  is  13.14  times  larger  than  the  ordinary  horse- 
power. 

The  Myriawatt  as  a  Basis  of  Boiler  Performance. — In  recent 
years,  due  to  the  tremendous  growth  in  the  electrical  industry, 
engineers  have  recognized  the  inconsistencies  of  the  boiler  horse- 
power unit  and  an  effort  has  been  made  by  the  national  engineer- 
ing societies  to  make  a  more  rational  standard  of  rating.  As  a 
consequence,  the  American  Institute  of  Electrical  Engineers  has 
proposed  that  the  Myriawatt  be  adopted  as  a  standard  of  boiler 


HOW  TO  COMPUTE  BOILER  HORSEPOWER  71 

rating  instead  of  the  Bl.  h.p.  A  Myriawatt  is  the  power  equiva- 
lent of  10,000  watts  or  10  kw.  which  converted  into  heat  units 
become  34,150  B.t.u.  per  hr.  Although  it  is  still  to  be  remem- 
bered that  the  Myriawatt  does  not  yet  make  output  and  input  of 
electrical  units  expressible  in  like  quantities,  since  output  is  usually 
expressed  in  kilowatts,  still  the  factor  of  10  furnishes  a  basis 
readily  convertible  and  makes  possible  a  change  in  units  without 
materially  upsetting  the  old  boiler  h.p.  range  of  capacity. 

If,  then,  a  boiler  evaporates  M  pounds  of  steam  per  hour  and 
the  total  heat  of  each  pound  of  steam  so  evaporated  be  H  and 
the  heat  of  liquid  represented  in  the  feed  water  be  hf,  then  the 
rating  of  a  boiler  in  Myriawatts  is  evidently 

Myriawatts  = 

Relationship  of  Boiler  Horsepower  and  Myriawatts. — Simi- 
larly, since  one  boiler  horsepower  is  equivalent  to  heat  absorp- 
tion of  33,479  B.t.u.  per  hour  and  a  myriawatt  to  34,150  B.t.u. 
per  hour,  then  we  may  convert  a  rating  in  Myriawatts  to  a  rating 
in  boiler  horsepower  or  vice  versa  by  the  relationship : 

Rating  in  boiler  horsepower  _  34,150 
Rating  in  Myriawatts""      ~  33,479 

The  Builder's  Rating. — In  the  commercial  evolution  of  the 
steam  boiler  there  has  grown  up  a  method  of  rating  boilers  by 
"rule  of  thumb "  process.  It  is  evident  that  the  area  of  the  steam 
generating  surface  of  the  boiler  actually  exposed  to  the  heated 
gases  of  the  furnace  has  something  to  do  with  the  capacity  of  the 
boiler.  For  different  designs  of  boilers,  however,  the  particular 
factor  to  be  applied  varies  widely.  It  has  become  of  common 
acceptance,  however,  that  10  sq.  ft.  of  boiler  surface  exposed  to 
the  furnace  heat  shall  be  considered  on  this  rule  of  thumb  com- 
parison as  equivalent  to  one  boiler  horsepower.  Hence  to  com- 
pute the  builder's  rating  of  a  boiler  we  must  compute  the  area 
in  square  feet  of  the  surface  exposed  to  the  furnace.  By  divid- 
ing this  area  A  by  ten  we  arrive  at  the  Builder's  Rating: 

/.  Bl.  h.p.  (Builder's  rating)  ==  —  (3) 

As  a  detailed  illustration,  let  us  take  the  case  of  a  Parker  boiler 
installed  at  the  Fruitvale  Power  Station  of  the  Southern  Pacific 
Company  in  Oakland,  California. 


72  FUEL  OIL  AND  STEAM  ENGINEERING 

This  boiler  is  made  up  of  three  banks  of  tubes  with  two  drums 
above,  half  exposed.     In  detail  we  compute  as  follows: 

Tubes    4  in.  diameter,  circumference  =  12.566  in.  =  1.0472  ft. 
Tubes  18  ft.  long  =  18  X  1.0472          =  18.85  sq.  ft.  of  H.  S. 
Tubes  20  ft.  long  =  20  X  1.0472          =  20.94  sq.  ft.  of  H.  S. 

Heating  Surface,  Bottom  Row  of  Tubes:  Heating  area 

20  tubes  with  18  ft.  of 

length  exposed  to  gases  =18.85  X  20  sq.  ft.  =  37.700 

Heating  Surface,  First  Pass: 
100  tubes  with  20  ft,  of 
length  exposed  to  gases  =  20.94  X  100  =  2094.00  sq.ft. 

Heating  Surface,  Second  Pass: 
80  tubes  with  20  ft.  of 
length  exposed  to  gases  =  20.94  X  80  =  1675.20  sq.  ft. 

Heating  Surface,  Third  Pass: 
80  tubes  with  20  ft.  of 

length  exposed  to  gases  =  20.94  X    80  =  1675.20  sq.  ft. 

Drums: 

2  drums  54  in.  diameter,  18^  ft.  of  length 
exposed  to  gases:  circumference  =  14.1  ft.; 
K  of  circumference  7  ft.  =  7  X  18.5  X  2  =  259.00  sq.  ft. 


Total .6080.40  sq.  ft. 

Hence,  we  have  that  the  builder's  rating  of  this  boiler  should  be 
Bl.  h.  p.  (Builders  rating)  =6>°^-4  =  608.04. 

To  Compute  Actual  Boiler  Rating. — Since  it  is  seen  from  the 
fundamental  definition  of  the  boiler  horsepower  that  the  stand- 
ard reference  boiler  generates  its  steam  from  water  at  212°F.  into 
steam  at  212°F.,  we  must  next  develop  a  factor  by  which  we  can 
reduce  ordinary  boiler  performances  of  high  temperatures  and 
pressures  to  this  fictitious  standard  before  we  can  proceed  fur- 
ther. The  next  chapter  will  be  devoted  to  this  consideration. 


CHAPTER  IX 

EQUIVALENT  EVAPORATION  AND  FACTOR  OF  EVAPORA- 
TION IN  FUEL  OIL  PRACTICE 

]N  the  previous  chapter  it  was  seen 
that  as  the  fundamental  definition 
of  the  boiler  horsepower  is  based 
upon  a  fictitious  boiler  that  receives 
its  feed  water  at  212°F.  and  then 
evaporates  it  into  dry  saturated 
steam  at  212°F.  and  atmospheric 
pressure,  we  must  now-  develop 
some  factor  by  which  we  can  reduce 
boiler  performances  as  actually  met 
with  in  practice  to  this  fictitious 
standard. 

In    order   also   to    compare   the 
steaming  qualities  of  two  different 
boilers   or  indeed  to  compare  the 
same    boiler   under    different   con- 
ditions of  water  supply  and  steam 
FIG.  48.— Piping  in  boiler  set-  generation,  it  is  necessary  that  some 
tlTrL  IrheerteakeTerheat    tempera"  standard  of  comparison  be  adopted. 

Thus    a    boiler    under   its   normal 

condition  of  operation  may  be  found  to  evaporate  13.61  Ib. 
of  water  per  Ib.  of  oil  fired  per  hour  when  taking  its  feed 
water  at  169. 1°F.  and  converting  it  into  superheated  steam  at 
a  temperature  of  527°F.  and  a  pressure  of  185.3  gage.  On  the 
other  hand,  the  identical  boiler,  when  steaming  under  overload 
conditions  of  a  feed  water  temperature  of  174.1°F.,  a  superheat 
temperature  of  536.9°F.  and  gage  pressure  of  194.1  Ib.  persq.  in. 
may  be  found  to  evaporate  only  13.17  Ib.  of  water  per  Ib.  of  oil 
fired,  even  though  the  same  quality  of  oil  be  used  in  each  in- 
stance. It  is  evident  then  from  sight  that  to  compare  these 
two  evaporative  quantities  without  taking  account  of  the  actual 
heat  transferred  from  the  fuel  to  the  steam  in  the  boiler  would  be 
a  possible  source  of  error. 

73 


74  FUEL  OIL  AND  STEAM  ENGINEERING 

The  Standard  that  Has  Been  Adopted. — To  avoid  inconsist- 
encies and  to  develop  some  rational  method  of  comparison, 
engineers  have  found  it  convenient  and  accurate  to  re- 
duce all  evaporative  quantities  of  a  boiler  to  a  definite  standard. 
In  order  to  follow  out  this  standardized  comparison,  all  steam 
generating  performances  of  boilers  read  as  if  the  boiler  took  its 
feed  water  at  212°F.  and  atmospheric  pressure,  and  converted 
it  into  dry  saturated  steam  at  212°F.  and  atmospheric  pressure, 
as  set  forth  in  the  standard  definition  of  the  boiler  horepower  in 
the  last  chapter.  It  is  clearly  evident  that  no  such  theoretical 


FIG.  49. — Platform  scales  and  tanks  for  water  measurement. 

The  boiler  immediately  to  the  right  of  the  platform  scales  is  under  test.  The  tank  below 
the  platform  scales  into  which  the  water  is  emptied  after  being  weighed,  is  utilized  to  fur- 
nish all  water  for  the  boiler  during  the  test.  At  the  beginning  of  the  test  a  hooked  gage 
registers  the  height  of  the  water  in  this  tank,  and  at  each  hourly  period  thereafter  suf- 
ficient water  is  weighed  and  emptied  into  it  from  the  tanks  above  to  maintain  this  exact 
level.  By  means  of  these  data,  properly  taken,  the  factor  of  evaporation  and  the  boiler 
horse-power  are  easily  computed. 

boiler  has  ever  existed,  yet  this  standard  of  comparison  is  found 
very  convenient.  Thus  in  any  case  of  boiler  performance,  if 
Me  represents  such  an  equivalent  or  comparative  standardized 
evaporation  in  Ibs.  of  water  per  Ib.  of  fuel,  and  Mn  the  Ib.  of 
water  actually  evaporated  in  the  boiler  under  conditions  of  test, 
we  may  now  invent  a  factor  to  be  known  as  the  factor  of  evapora- 
tion, Fe,  whereby  such  performances  may  be  readily  reduced: 

Me    =    Mw.  Fe  (1) 

In  the  same  way,  the  equivalent  evaporation  of  water  per  hour 
may  be  computed  from  the  formula 

Mek  =  Mwh.    Fe  (2) 

wherein  M ^  and  Mwh  represent  hourly  conditions  of  evaporation. 


EQUIVALENT  EVAPORATION  75 

Let  us  next  analyze  the  factor  of  evaporation  and  see  how  we 
may  actually  compute  its  value  for  any  given  case.  We  have 
previously  found  that  in  the  operation  of  the  boiler,  steam  appears 
in  three  different  conditions  or  qualities,  namely  in  what  is 
known  as  dry  saturated,  wet  steam,  or  superheated  steam. 
Let  us  then  consider  the  valuation  of  the  factor  of  evaporation 
for  these  three  distinct  instances. 

Dry  Saturated  Steam.  —  In  the  case  of  dry  saturated  steam, 
the  water  enters  the  boiler  already  possessing  a  heat  of  liquid  h/ 
corresponding  to  its  entrance  temperature  which  may  be  readily 
found  in  the  steam  tables.  This  water  is  next  converted  into  dry 
saturated  steam  which  has  a  total  heat  (He)  corresponding  to  the 
pressure  at  which  the  evaporation  takes  place.  Consequently 
the  actual  heat  which  has  been  transferred  from  the  boiler  shell 
to  the  water  is  (He  —  hf)  heat  units.  But  to  evaporate  one  pound 
of  water  at  212°F.  into  dry  steam  at  212°F.  requires  970.4  heat 
units.  Hence  if  Mw  pounds  of  water  are  evaporated  under  test 
conditions,  the  number  of  pounds  Me  under  standardized  condi- 

tions would  evidently  be  Mw  —  Syn  4     •     Therefore  for  dry  sat- 


urated steam 

Fe  (dry  saturated  steam)  =    ^79^  (3) 

Thus  in  the  case  of  a  boiler  which  takes  its  feed  water  at  101.8° 
F.  and  converts  it  into  dry  saturated  steam  at  180  Ib.  pressure 
per  square  inch,  from  the  steam  tables  we  find  that  He  is  1196.4 
and  hf  is  69.8,  hence  the  factor  of  evaporation  is 

1196.4  -  69.8 
-- 


Wet  Steam.  —  In  the  case  of  wet  steam  all  of  the  water  entering 
the  boiler  is  not  converted  into  steam.  As  a  consequence  a  cer- 
tain portion  of  heat  (he  —  hf)  is  required  to  raise  the  temperature 
of  the  water  from  entrance  temperature  t/  to  the  temperature  of 
evaporation  te  and  if  only  Xc  parts  of  a  Ib.  are  then  evaporated 
into  steam,  only  XeLe  B.t.u.  are  required  to  accomplish  this  result. 
Hence,  the  total  heat  required  per  Ib.  of  water  so  evaporated  is 
(he  +  XeLe  -  hf). 

As  a  consequence  the  factor  of  evaporation  in  this  case  ma^ 
from  similar  reasoning  be  expressed  by  the  formula 

(he   +   XeLe   ~    h  f)  ,.>. 

Fe(wet  steam)  =  ~~~~ 


76  FUEL  OIL  AND  STEAM  ENGINEERING 

As  an  instance  showing  the  application  of  this  formula  let  us 
assume  that  the  boiler  above  mentioned  did  not  evaporate  the 
water  into  dry  steam  but  that  upon  investigation  it  was  found  to 
contain  5  per  cent,  moisture.  •  What  now  is  its  factor  of  evapora- 
tion? From  the  steam  tables  we  find  that  he  is  345.6,  Le  is 
850.8  and  h/  is  69.8.  Therefore  the  factor  of  evaporation  is 

345.6  +  -95  X  850.8  -  69.8 
Fe  =  ~" 


Superheated  Steam.  —  In  the  third  instance  steam  is  not  only 
evaporated  to  a  dry  saturated  condition,  but  is  finally  sent  from 
the  boiler  in  a  superheated  condition.  The  steam  tables  are  so 
arranged  that  we  may  find  the  heat  necessary  to  raise  the  total 
heat  of  superheated  steam  when  its  pressure  and  temperature 
are  known.  Considering  that  the  water  entered  the  boiler  at  32°F. 
let  us  then  call  H8  the  total  heat  of  superheated  steam.  Since 
now  the  water  entered  the  boiler  with  a  heat  of  liquid  equal  to 
hf  the  actual  heat  entering  each  Ib.  of  steam  evaporated  in  the 
boiler  under  these  conditions  is  (Ha  —  hf)  heat  units.  Hence 
in  this  instance  the  factor  of  evaporation  is  likewise  from  similar 
reasoning  computed  by  the  formula: 

^^(superheated  steam)  =      *         f  (5) 

\j  i  \J  »rt 

To  follow  up  the  same  example  as  set  forth  in  the  preceding 
illustration  let  us  assume  that  the  steam  is  evaporated  under  the 
conditions  hitherto  mentioned,  but  that  it  appears  superheated 
to  the  extent  of  100°.  Looking  in  the  steam  tables  we  find  that 
the  total  heat  H8  of  superheated  steam  at  180  Ib.  pressure  and 
100°  superheat  is  1254.3  and  that  the  heat  of  liquid  hf  is  69.8, 
consequently  the  factor  of  evaporation  is 

1254.3  -  69.8 
~970l" 

To  Compute  the  Boiler  Horsepower.  —  Since  now  by  means  of 
formula  (2),  we  are  enabled  to  compute  the  equivalent  evapora- 
tion of  M  eh  in  pounds  of  water  per  hour  that  the  boiler  under  test 
would  evaporate  were  it  taking  its  feed  water  at  212°F.  and  con- 
verting it  into  dry  saturated  steam  at  the  same  temperature, 
we  can  at  once  compute  the  horsepower  of  the  boiler.  Under 
such  conditions  of  operation  for  every  34.5  Ib.  of  water  evapo- 


EQUIVALENT   EVAPORATION  77 

rated  per  hour,  the  boiler  is  developing  one  boiler  horsepower. 
Hence  to  compute  the  boiler  horsepower,  we  write  the  formula: 

Bl.  hp.  =  g*  («) 

Thus  if  a  boiler  has  an  equivalent  evaporation  of  23,350  Ib.  of 
water  per  hour,  its  horsepower  is  found  to  be 


Bl.  hp.  =-  =676.7 

o4.o 

We  could  of  course  develop  an  expression  for  the  computation 
of  boiler  horsepower  by  taking  into  consideration  the  heat 
absorbed  by  the  generation  of  steam  per  hour.  For  in  our  dis- 
cussion in  the  previous  chapter  it  was  shown  that  one  boiler  horse- 
power is  equivalent  to  the  absorption  of  33,479  heat  units  per 
hour.  Hence,  by  computing  the  heat  absorbed  by  the  total 
pounds  of  steam  generated  per  hour  and  dividing  this  by  33,479, 
we  can  compute  boiler  horsepower  and  arrive  at  the  same  answer 
as  given  in  the  above  formula.  It  is  better,  however,  for  the 
beginner  to  follow  fundamental  definitions  rather  than  attempt 
too  many  short  cuts  to  gain  quick  results. 

In  conclusion  the  important  relationship  to  bear  in  mind  is 
the  vast  difference  between  the  socalled  mechanical  horsepower 
and  the  boiler  horsepower  which  was  brought  out  in  the  previous 
discussion.  With  this  relationship  firmly  fixed  it  must  be  re- 
membered that  equivalent  evaporation  is  such  an  evaporation  as 
would  be  brought  about  by  taking  in  water  into  the  boilers  at 
212°F.  and  evaporating  it  into  dry  saturated  steam  at  212°F.  and 
atmospheric  pressure.  The  formulas  deduced  above  for  equiva- 
lent evaporation  and  factor  of  evaporation  enable  us  to  do  this. 


CHAPTER  X 


HOW  TO  DETERMINE  QUALITY  OF  STEAM 

TEAM  as  used  in  engineering 
practice  is  said  to  be  wet,  dry 
saturated  or  superheated,  de- 
pending upon  the  degree  to 
which  heat  has  been  applied  in 
its  generation. 

Wet  Steam. — As  its  name 
implies,  wet  steam  is  steam  in 
which  are  suspended  small 
globules  or  particles  of  water. 
Since  such  globules  or  particles 
of  water  indicate  that  insufficient 
heat  has  been  applied,  and  con- 
sequently steam  generation  is 
imperfect,  it  is  the  function  of 
all  good  boilers  to  generate 
steam  as  free  from  water  as 
possible. 

Although  steam  be  generated 
dry  or  even  superheated  it  may, 
however,  after  passing  through 
conducting  pipes  appear  at  the 
power  generating  unit  in  a  wet  condition.  Hence  the  determina- 
tion of  moisture  content  and  the  heat  loss  due  to  its  presence  is  an 
important  one  in  steam  engineering. 

Let  us  assume  X  to  be  the  proportion  by  weight  of  dry  steam 
that  exists  in  wet  steam.  Then  the  total  heat  represented  in 
every  pound  of  such  wet  steam  at  temperature  t  is 


FIG.  50. — Thermometer  inserted  for 
superheat  measurement. 


H,  =  ht  +  XL, 


(1) 


This  is  evident  at  once  when  we  consider  that  to  raise  each  pound 
of  original  water  from  32°F.  to  the  temperature  t,  it  required  ht, 
heat  units.  On  the  other  hand  since  a  proportion  by  weight 

78 


HOW  TO  DETERMINE  QUALITY  OF  STEAM  79 

equal  to  X  has  actually  gone  into  steam,  the  heat  required  in 
the  latent  heat  of  evaporation  is  but  XLt. 

Dry  Saturated  Steam. — As  one  may  infer  from  the  heading, 
saturated  steam  that  contains  no  moisture  is  called  dry  saturated 
steam.  In  the  chapter  on  properties  of  water  the  determination 
of  its  total  heat  was  illustrated  quite  fully.  We  may,  however, 
derive  the  equation  for  total  heat  of  dry  saturated  steam  from  the 
equation  above  for  wet  steam.  For  in  this  latter  instance  since 
no  water  is  present,  evidently  X  becomes  equal  to  unity.  Hence 
for  dry  saturated  steam 

Ht  =  ht  +  Lt  (2) 

Superheated  Steam. — It  has  been  hitherto  pointed  out  that 
when  water  is  being  evaporated  into  steam  the  temperature  re- 
mains constant  until  all  the  water  disappears.  So  long,  however, 
as  steam  remains  in  contact  with  the  water  from  which  it  is  being 
formed  it  is  either  diy  or  wet  steam  and  its  temperature  cannot 
be  raised  above  that  which  normally  represents  the  boiling  point 
of  water  for  the  pressure  under  which  the  steam  is  being 
generated. 

It  has,  however,  been  found  of  immense  economic  value  in 
steam  engineering  practice  to  actually  use  steam  that  is  heated 
over  a  hundred  degrees  in  excess  of  the  temperature  at  which 
saturated  steam  may  be  generated  under  the  existing  pressure 
conditions.  It  is  seen  that  such  steam  must,  of  course,  first 
become  absolutely  dry  and  then  any  additional  heat  that  may  be 
added  goes  toward  raising  its  temperature  if  the  pressure  be  kept 
constant. 

This  is  accomplished  in  the  modern  steam  generating  units  by 
conducting  the  saturated  steam  from  the  main  drums  in  which 
it  is  generated  and  passing  it  through  tubes  exposed  to  highly 
heated  portions  of  the  boiler  furnace.  Such  a  system  of  tubes 
is  known  as  a  superheater.  The  steam  quickly  absorbs  sufficient 
heat  to  completely  dry  it  and  still  further  raise  its  temperature. 

Computation  of  Total  Heat  of  Superheated  Steam. — If  a 
definite  constant  quantity  of  heat  were  required  to  superheat  a 
pound  of  steam  one  degree  in  temperature  for  all  ranges  of  tem- 
perature and  pressure,  we  could  write  down  a  comparatively 
simple  formula  for  arriving  at  the  total  heat  of  superheated  steam. 
Since,  however,  this  specific  heat  constant  has  a  wide  range  of 
.46  to  .60  it  is  impossible  to  do  so. 


80  FUEL  OIL  AND  STEAM  ENGINEERING 

Hence  in  each  case  of  temperature,  pressure  and  degree  of 
superheat,  we  must  refer  to  steam  tables  in  order  to  find  the 
proper  value  of  total  heat  of  superheated  steam.  And,  indeed, 
this  too  is  necessary  to  find  all  the  other  constants  that  relate  to 
superheated  steam. 

The  fundamental  definition  remains  the  same,  however — 
namely  that  the  quantity  of  steam  required  to  raise  one  pound 
of  water  from  32°F.  to  the  temperature  t  corresponding  to  the 
boiling  point  of  water  for  the  pressure  at  which  the  steam  is 
generated,  added  to  the  latent  heat  of  evaporation  for  this  pres- 
sure, together  with  such  additional  heat  as  may  be  required  to 
raise  the  one  pound  of  now  dry  saturated  steam  to  the  degree  of 
superheat  given,  is  known  as  the  total  heat  of  superheated  steam 
H8.  Expressing  this  algebraically  we  have 

Hs  =  ht  +  Lt  +  Cpm  (ts  -  t)  (3) 

As  an  example  let  us  suppose  that  superheated  steam  is  being 
generated  at  ordinary  atmospheric  pressure  and  delivered  at  a 
temperature  of  312°F.  We  will  suppose  that  the  mean  specific 
heat  Cpm  for  the  range  of  temperature  and  pressure  under  con- 
sideration is  say  0.46.  Then  from  the  tables,  we  find 

ht  =  180.     Lt  =  970.4     ts  =  312°. 

t  =  212°.     Cpm  =     0.46 
.*.  Hs  =  180  +  970.4  +  0.46  (312  -  212) 
=  180  +  970.4  +  46  =  1196.4  B.t  u. 

It  is  most  important  that  the  student  should  remember  that 
although  the  value  Hs  may  be  taken  directly  from  the  steam  tables, 
still  it  is  based  on  the  several  steps  above  taken.  In  many  steam 
engineering  problems  this  separate  analysis  or  dissecting  must  be 
done  so  it  is  well  to  clinch  this  matter  without  delay. 

Steam  Calorimeters. — The  word  calorimeter  often  causes  con- 
siderable confusion  because  there  are  two  entirely  different  and 
distinct  types  of  mechanism  that  bear  this  name  in  engineering 
practice.  Fundamentally  it  means  "a  measurer  of  heat."  In 
order  to  determine  the  heat  contained  in  fuel  an  instrument  known 
as  a  calorimeter  is  employed  which  will  be  described  in  later  pages. 
At  this  point,  however,  we  shall  now  proceed  to  describe 
several  types  of  an  instrument  that  bears  the  same  name 
and  yet  is  entirely  different  both  in  design  and  in  aim  to  be 
accomplished. 


HOW  TO  DETERMINE  QUALITY  OF  STEAM 


81 


The  steam  calorimeter  is  an  instrument  used  in  steam  engineer- 
ing practice  to  determine  the  exact  quality  of  steam,  whether  it 
be  wet,  dry  saturated,  or  superheated,  and  to  what  extent. 
Since  the  thermometer  and  the  carefully  calibrated  pressure  gage 
constitute  the  easiest  and  most  direct  method  of  ascertaining 
superheat,  the  uses  of  the  steam  calorimeter  are  usually  limited 
to  determination  of  moisture  in  wet  steam. 

The  Determination  of  Superheat. — The  method  of  ascertain- 
ing superheat  will  now  be  set  forth. 


3**9'» 

T*n-~ 
V«/. 


f>f*»ot°?r 

ri-~0'-,fr9r     j 

'"  ^^^  |  .- •  J-ff.'-rvffd  jv|?~ 

^<r-y-  —  ~>Ai.*r/..  i 

•7 
^•J»i»rt>*a\od  J> 


'feo-n  Ja't?-,  J'<7A-« 


FIG.  51. — Temperature  determination  for  superheated  steam. 
In  taking  the  temperature  for  superheater  steam  a  thermometer  should  be  inserted  as 
near  the  superheater  drum  as  practicable.  The  thermometer  has  suspended  at  its  side  a 
second  thermometer  in  order  to  ascertain  the  proper  correction  to  be  made  for  that  portion 
emerging  from  the  bath  in  which  the  main  thermometer  rests  so  that  the  stem  correction 
may  be  made.  In  the  illustration  may  be  seen  the  point  at  which  the  thermometer  well  for 
ascertaining  the  superheated  steam  temperature  was  inserted  in  finding  the  superheat  for 
an  installation  in  Oakland,  California. 

A  thermometer  is  inserted  in  the  outlet  of  the  superheater 
drum,  and  the  temperature  read,  and  at  the  same  instant  the 
pressure  of  the  superheater  drum  is  read  on  a  steam  gage  at- 
tached to  this  drum.  In  order  to  correct  for  the  exposed  stem  of 
the  superheat  thermometer  a  separate  thermometer  is  attached 
to  the  stem  of  the  former.  Suppose  the  superheat  thermometer 
reads  529°F.,  and  300°  of  its  mercury  column  projects  above  the 
thermometer  well;  suppose  also  the  attached  thermometer  reads 
141°F.  Then,  by  formula  (6)  on  page  40,  the  stem  correction 
equals 

0.000086  X  300  X  (529  -  141)  =  10°F. 


82  FUEL  OIL  AND  STEAM  ENGINEERING 

The  true  temperature  of  the  superheated  steam  is  therefore  529  + 
10  =  539°F.  If  now  the  steam  gage  reads  178.5  Ib.  per  sq.  in. 
and  the  atmospheric  pressure  is  14.7  Ib.  per  sq.  in.  we  proceed  as 
follows : 

The  absolute  pressure  of  the  superheated  steam  is  the  sum  of 
178.5  and  14.7  which  is  193.2  Ib.  per  sq.  in.  Referring  to  steam 
tables,  we  find  that  water  boils,  or  rather  saturated  steam  is 
generated,  at  a  temperature  of  379°F.  when  under  a  pressure  of 
193.2  Ib.  per  sq.  in.  Hence,  the  superheat  of  the  steam  under 
consideration  is  the  difference  of  539°  and  379°,  which  is  160°F. 

Determination  of  Moisture  in  Wet  Steam. — There  are  many 
methods  that  may  be  used  in  determining  the  moisture  content 
of  wet  steam.  The  particular  method  to  be  employed  depends 
much  upon  the  accuracy  desired  and  the  degree  or  intensity  of 
the  moisture  content  present. 

The  Barrel  or  Tank  Calorimeter. — In  this  method,  which 
should  never  be  used  except  for  approximate  results,  the  steam 
is  allowed  to  pass  up  through  a  barrel  of  water.  Of  course,  the 
steam  at  once  condenses  into  water  and  the  resulting  mixture  with 
the  water  in  the  barrel  raises  the  temperature.  By  taking  the 
pressure  of  the  steam  and  the  two  temperatures  of  the  water — 
the  one  before  applying  the  steam  and  the  other  after  its  appli- 
cation together  with  the  weights  of  the  water  involved,  we  may  at 
once  write  a  mathematical  relationship  to  determine  the  moisture 
content. 

If  we  neglect  radiation  and  other  stray  losses,  the  heat  gained 
by  the  water  in  the  barrel  is  equal  to  that  lost  by  the  steam  under 
test. 

In  all  the  subsequent  discussions  in  this  chapter  let  us  let 
0  subscripts  represent  conditions  of  steam  in  the  boiler;  1  sub- 
scripts, the  initial  conditions  in  the  barrel;  2  subscripts,  the  final 
conditions  in  the  barrel;  and  W  will  represent  the  weights 
involved. 

The  total  heat  of  each  pound  of  entering  steam  is  by  equation 
(1)  found  to  be  (ho  +  XoLo)  and  since  after  this  pound  of  con- 
densed steam  mixes  with  the  water  in  the  barrel  it  still  has  hz 
units  of  -heat,  there  is  then  a  net  loss  of  (ho  +  XoLo  —  A  2)  heat 
units.  In  the  same  way  each  pound  of  water  in  the  barrel  gains 
(hz  —  hi)  heat  units.  If  Wo  units  of  steam  are  involved  and 
Wi  units  of  water  are  found  in  the  barrel  at  the  beginning  of 
the  test,  we  know  then,  since  heat  lost  by  the  steam  is  equal 


HOW  TO  DETERMINE  QUALITY  OF  STEAM 


83 


to  heat  gained  by  the  water,  neglecting  radiation  and  other 
losses,  that 

Wo  (ho  -\-  XoLo  —  ^2)  —  Wi  (h2  —  hi) 

y       Wi(h2  —  hi)  —  Wi)(ho  —  h2)  .  . 

'  '  ^  °  =  ^lrr~T  (4) 


As  an  example,  it  was  found  in  a  test  that  a  steam  main  under 
90  Ib.  pressure  (gage)  deposited  3  Ib.  of  condensed  steam  into  a 


FIG.  52. — Auxiliary  steam  apparatus  at  left  with  boiler  at  right  showing  soot 
blower  and  auxiliary  steam  piping,  Long  Beach  Plant,  Southern  California 
Edison  Company. 


vessel  that  contained  27  Ib.  of  water  at  62°F.,  thereby  raising  the 
temperature  to  175°F.  We  compute  the  proportion  of  dry  steam 
in  the  main  as  follows: 

Po  =  90  Ib.  per  sq  in.  (gage)  =  104.7  Ib.  per  sq.  in.  abs, 
Wi  =  27  Ib.,  W0  =  3  Ib.     ti  =  62°F.,  t2  =  175°F. 


84  FUEL  OIL  AND  STEAM  ENGINEERING 

Hence  from  steam  tables — 

Lo  =  885.4,  ho  =  301.8,  hi  =  30.1,  h*  =  142.9 

27(142.9  -  30.1)  -  3(301.8  -  142.9) 
'   'Xo=  3  X  885.4 

. ' .  X0  =  96.8  per  cent,  dry  steam  in  steam  under  test. 


FIG.  53. — Side  view  of  oil  fired  Stirling  boilers  showing  the  steam  piping, 
soot  blower,  piping  and  explosion  doors,  station  A,  Pacific  Gas  and  Electric 
Company,  San  Francisco. 

Surface  Condenser  Tank  Calorimeter. — This  method  varies 
from  the  one  just  set  forth  in  that  the  condensed  steam  does 
not  mingle  with  the  water  in  the  barrel.  To  accomplish  this  the 
steam  is  passed  through  a  coil  of  piping  which  is  inserted  in  the 
tank.  As  the  steam  comes  in  contact  with  the  cooling  surface 
of  this  pipe,  it  is  condensed  into  water  and  of  course  the  heat 
thus  liberated  or  given  out  is  absorbed  by  the  water  in  the  tank 
and  its  temperature  correspondingly  raised.  Hence  in  this 
instance,  it  is  necessary  to  weigh  the  water  in  the  tank  and  the 


HOW  TO  DETERMINE  QUALITY  OF  STEAM  85 

condensed  steam  discharged  through  the  coil.  It  is  also  neces- 
sary to  take  the  pressure  of  the  steam  under  observation  and 
to  note  the  temperature  of  the  tank  of  water  before  and  after 
application  as  well  as  the  temperature  of  the  water  discharged 
from  the  coils. 

Proceeding  by  similar  reasoning  as  set  forth  in  the  former  in- 
stance, the  heat  lost  by  each  pound  of  steam  is  sure  to  be  (ho  + 
XoLo  —  hs),  wherein  the  subscript  3  is  to  denote  the  condition 
of  the  steam  condensed  into  water  as  it  emerges  from  the  coil. 
The  heat  gained  by  each  pound  of  water  in  the  tank  is  also  seen 
to  be  (h2  —  hi)  heat  units.  Hence  if  Wo  Ib.  of  condensed  steam 
are  discharged  and  W\  Ib.  of  water  are  found  in  the  tank,  since 
the  heat  lost  by  the  steam  is  equal  to  that  gained  by  the  water, 
neglecting  radiation  and  other  minor  losses,  we  have 


v       Wi(hz  —  hi)  --  W0(h0  —  hs)  /c, 

.   .  AO=  ~W~L~  ^  ' 

To  illustrate,  let  us  assume  that  one  pound  of  steam  at  a  pres- 
sure of  100  Ib.  per  sq.  in.  absolute  is  passed  through  coils  immersed 
in  a  tank  containing  ten  pounds  of  water  at  an  initial  tempera- 
ture of  100°F.  At  the  conclusion  of  the  condensation  the 
water  in  the  tank  is  found  to  be  at  a  temperature  of  204. 5°F., 
while  that  emerging  from  the  coils  is  210°F.  The  quality  of 
the  steam  is  at  once  found  by  substitution  in  the  formula  as 
follows: 

From  the  test  data  we  have  pQ  =  100  Ib.,  Wi  =  10  Ib.,  Wo 
=  1  Ib.,  ti  =  100°F.,  *2  =  204.5°F.,  and  t»  =  210°F.  From 
the  steam  tables  we  find  hi  =  68,  h2  =  172.5,  hs  =  178,  ho  = 
298.3,  Lo  =  888.0. 

10  (172.5  -  68)  -  1  (298.3  -  178) 
1  X888 

Since  the  quality  of  steam  is  greater  than  unity,  it  is  evident 
that  the  steam  in  this  instance  is  superheated. 

The  principle  upon  which  the  more  accurate  steam  calori- 
meters operate  is  in  general  accomplished  along  similar  lines. 
We  shall,  however,  reserve  further  discussion  on  the  subject 
until  the  next  chapter  wherein  we  shall  deal  at  length  with 
calorimeters* 


CHAPTER  XI 
THE  STEAM  CALORIMETER  AND  ITS  USE 

We  come  now  to  a  consideration  of  the  methods  used  in  steam 
engineering  practice  to  accurately  determine  the  moisture  con- 
tent of  saturated  steam.  In  the  preceding  chapter  certain 
approximate  methods  were  set  forth,  but  in  the  following  discus- 
sion it  will  be  seen  that  by  care  and  patience  the  moisture  content 
of  saturated  steam  may  be  ascertained  with  a  wonderful  degree 
of  accuracy. 

The  Chemical  Calorimeter. — The  Chemist  has  a  method  of 
determining  the  moisture  content  which  finds  little  application 
in  the  steam  engineering  laboratory,  but  in  the  chemist's  labora- 
tory it  is  performed  with  a  remarkable  degree  of  accuracy. 
Certain  salts  absorb  moisture  held  in  a  vapor.  Hence  by  passing 
wet  saturated  steam  over  such  salts,  the  moisture  content  is 
taken  from  the  steam  and  by  weighing  the  moisture  so  absorbed 
the  degree  of  moisture  held  in  suspension  is  ascertained. 

The  Throttling  Calorimeter. — By  reference  to  the  steam  tables 
it  is  seen  that  when  saturated  steam  exists  at  say  200  Ib.  pressure 
per  sq.  in.,  each  pound  of  steam  represents  a  storage  of  heat  equal 
to  1197.6  B.t.u.  For  it  is  seen  from  the  steam  tables  that  it 
took  354.4  B.t.u.  to  bring  the  original  pound  of  water  from  32°F. 
to  its  boiling  point  and  then  an  additional  843.2  B.t.u.  to  evapo- 
rate this  water  into  dry  saturated  steam. 

Let  us  suppose  for  a  minute  this  steam  at  200  Ib.  per  sq.  in. 
were  allowed  to  flow  through  an  orifice  and  expand  into  a  chamber 
which  was  at  but  14.7  Ib.  per  sq.  in.  From  the  steam  tables  it 
is  seen  that  saturated  steam  existing  under  such  a  pressure  holds 
in  storage  but  1150.4  B.t.u.  What  then  becomes  of  the  differ- 
ence between  1197.6  B.t.u.  and  1150  B.t.u.  represented  by  the 
heat  held  in  storage  in  the  two  instances?  Evidently  if  the  main 
at  the  lower  temperature  be  well  hooded  so  that  no  heat  escapes, 
the  heat  given  out  must  go  toward  superheating  the  steam  at  the 
lower  pressure.  Since  the  specific  heat  of  superheated  steam  at 
the  lower  pressure  is  about  0.47,  the  47.2  B.t.u.  that  are  liberated 

86 


THE  STEAM  CALORIMETER  AND  ITS  USE 


87 


would  evidently  superheat  the  steam  about  100°.  The  actual 
measurement,  then,  of  this  superheat  gives  us  at  once  a  most 
accurate  method  of  determining  the  quantity  of  moisture  present 
in  the  steam  at  the  original  pressure.  For  if  we  find  that  the 
steam  is  superheated  only  25°F.,  instead  of  100°F.,  evidently  some 
of  the  mixture  must  have  been  water,  for  otherwise  its  existence 
at  the  higher  temperature  as  steam  would  aid  in  superheating 
still  further  the  lower  temperature. 


Thermometer 


FIG.  54. — The  throttling  calorimeter  and  the  sampling  nozzle. 

In  the  typical  throttling  calorimeter,  steam  is  drawn  from  a  vertical  main  through  the 
sampling  nipple,  then  passed  around  the  first  thermometer  cup,  then  through  a  one-eighth 
inch  orifice  in  a  disk  between  two  flanges,  and  lastly  around  the  second  thermometer  cup 
and  to  the  atmosphere.  Thermometers  are  inserted  in  the  wells,  which  should  be  filled 
with  mercury  or  heavy  cylinder  oil.  Due  to  the  fact  that  the  heat  content  in  the  steam 
under  the  expanded  condition  with  which  it  reaches  the  second  thermometer,  is  much  less, 
the  heat  thus  liberated  superheats  the  steam  at  this  point  and  thus  a  means  is  given  for 
ascertaining  the  moisture  originally  in  the  steam  sample. 

A  throttling  calorimeter,  then,  is  simply  a  contrivance  by 
which  we  allow  steam  to  pass  from  its  high  pressure  through  a 
small  opening  where  its  temperature  and  pressure  are  taken  be- 
fore it  passes  out  into  the  atmosphere.  Prior  to  its  passage 
through  the  small  opening,  the  temperature  and  pressure  of 
the  steam  is  noted.  Let  us  denote  by  "s"  subscripts  the  condi- 
tions of  superheated  steam  in  the  low  pressure  chamber,  "o" 
subscripts  the  steam  in  the  steam  main,  and  "3"  subscripts  satu- 
rated steam  at  the  pressure  of  the  low  pressure  chamber. 

Each  pound  of  wet  steam  in  the  steam  main  has  X0  parts  by 
weight  existing  as  dry  steam.  Hence  the  total  heat  represented 
in  each  pound  of  this  steam  is  evidently  (XoL0  +  h0)  heat  units 


88  FUEL  OIL  AND  STEAM  ENGINEERING 

as  seen  from  close  inspection.  In  the  same  manner  each  pound' 
of  steam  in  the  lower  pressure  chamber  holds  in  storage 
[#3  +  Cpm(ta  —  £3)]  heat  units  as  seen  from  previous  reasoning. 
Since  no  heat  is  allowed  to  escape,  evidently  these 

XoL0  +  h0  =  #3  +  Cpm(ts  -  t.) 

expressions  are  equal  one  to  the  other,  or 

Cpm  for  the  low  pressures  has  a  value  of  0.47,  hence,  we  have 

v        #3  +  0.47  (t.-ts)-hc  _Hs-h0 

Ao      —  T  T  (1) 

L/o  L/o 

in  which  H 8  is  the  total  heat  of  superheated  steam  in-  the  low 
pressure  chamber.  Its  numerical  value  may  be  taken  directly 
from  the  steam  tables  when  the  pressure  and  degree  of  superheat 
are  known. 

As  an  illustration,  let  us  assume  that  the  pressure  in  the  steam 
main  is  153.6  Ib.  per  sq.  in.  abs.  and  that  its  temperature  is  found 
to  be  362.9°F.,  thus  indicating  at  once  that  the  steam  is  saturated 
and  not  superheated.  After  it  has  expanded  into  the  low  pres- 
sure chamber  it  is  found  to  have  a  temperature  of  261. 3°F.  and 
a  pressure  of  14.8  Ib.  per  sq.  in.  absolute. 

From  the  steam  tables  we  find  L0  =  859.6;  h0  =  334.8;  H3 
=  1150.5;  ts  =  261.3;  «,  =  212.4°F. 

v   _  1150.5-334.8  +  0.47  (261.3-212.4)  _  A  nty, 
•'•A*~  859.6 

Therefore  the  steam  is  evidently  97.58  per  cent.  dry. 

Normal  Reading  of  the  Calorimeter. — For  accurate  work  it 
is  necessary  to  make  a  correction  for  the  radiation  loss  from  a 
calorimeter.  This  may  be  done  by  taking  readings  on  the  in- 
strument when  absolutely  dry  saturated  steam  is  passing  through 
it.  This  reading  is  called  the  Normal  Reading  of  the  calorimeter. 
A  boiler  that  is  standing  by  without  a  fire  under  it  but  with  pres- 
sure up  will  deliver  practically  dry  steam.  It  is,  therefore,  pos- 
sible to  secure  the  normal  reading  of  the  calorimeter  right  in 
place,  by  shutting  off  the  oil  burners  and  allowing  the  circulation 
within  the  boiler  to  come  to  rest.  A  more  accurate  method  of 
obtaining  the  normal  reading  is  shown  in  the  illustration  on  page 
89.  In  this  arrangement  the  calorimeter  is  supplied  from  near 
the  top  of  a  horizontal  pipe  containing  quiescent  steam,  a  drain 
being  provided  to  remove  the  moisture  from  the  bottom. 


THE  STEAM  CALORIMETER  AND  ITS  USE  89 

By  using  the  normal  reading  (tn)  in  equation  (1)  we  have 

xn  =  ^ 


OA7(tn  -  tt)  -  h, 


Here  Xn  is  the  quality  of  steam  indicated  by  the  calorimeter 
when  in  reality  the  steam  is  dry.     X0  is  the  quality  of  the  actual 


Steam  Gauge 


'hermometer 


rain  Valve 
Valve  Cracked 


Calorimeter 


A  suggestion  for  a  steam  calorimeter  attachment  for  determining  normal  read- 
ing of  calorimeter.      (See  page  88.) 

steam  under  test,  as  indicated  by  the  same  calorimeter.     By 
subtracting  one  from  the  other  we  have  the  true  moisture 


~V  "V 

n 


0.47  (*.,  -  tt)  - 


Li0 

OA7(tn  -  t8) 


Thus  in  the  foregoing  example,  let  us  suppose  the  normal  read- 
ing of  the  calorimeter  thermometer  was  290°F.  Then  the  true 
moisture  in  the  steam  becomes 

.-""5U  •"'-'"'"' 

The  steam  therefore  contains  1.57  per  cent,  moisture. 


90  FUEL  OIL  AND  STEAM  ENGINEERING 

The  Limitations  of  the  Throttling  Calorimeter.—  A  little 
consideration  of  the  underlying  principle  of  the  throttling  cal- 
orimeter brings  to  light  a  definite  range  of  limitation  to  its  use- 
fulness. It  will  be  remembered  that  this  fundamental  principle 
consists  in  liberating  sufficient  heat  at  the  lower  pressure  not 
only  to  evaporate  any  moisture  that  may  exist  but  to  actually 
superheat  the  entire  mixture.  If  there  is  not  sufficient  heat  lib- 
erated, that  is  if  too  much  water  is  held  in  suspension  in  the  satu- 
rated steam,  the  steam  at  the  lower  pressure  fails  to  become 
superheated  and  hence  we  have  no  means  of  measurement. 

Thus  if  steam  pass  from  100  Ib.  absolute  pressure  per  sq.  in. 
to  30  Ib.  absolute  pressure  per  sq.  in.,  the  total  heat  at  the  upper 
pressure  is  (XoL0  +  ho)  which  from  the  steam  tables  becomes 
(Jf  0888  +  298.3)  heat  units  and  that  at  the  lower  pressure  is 
H3,  or  1163.9,  if  it  be  not  at  all  superheated.  Hence  we  have 

+  298.3  =  1163.9 


This  means  that  if  there  is  a  greater  moisture  content  than  2.52 
per  cent,  the  steam  calorimeter  will  fail  to  work  because  the  mix- 
ture in  the  lower  pressure  space  does  not  become  superheated. 

If  instead  of  having  the  low  pressure  of  30  Ib.  absolute  per 
square  inch,  the  steam  in  the  calorimeter  had  been  throttled  down 
to  14.7  Ib.  the  value  of  H3  would  have  been  1150.4  instead  of 
1163.9  so  that  X0  would  become  0.9597  and  the  limit  of  the  calori- 
meter in  this  case  would  be  4.03  per  cent,  of  moisture. 

Again  if  instead  of  steam  at  100  Ib.  absolute  pressure  we  had 
steam  at  200  Ib.  and  allowed  the  sample  in  the  calorimeter  to  be 
throttled  down  to  14.7  Ib.  it  may  be  found  in  the  same  way  that 
the  limit  of  the  calorimeter  is  5.66  per  cent,  of  moisture.  It  is 
thus  seen  that  the  greater  the  difference  in  pressure  between  the 
high  pressure  and  the  low  pressure  in  the  calorimeter,  the  greater 
is  the  range  of  the  calorimeter. 

The  Electric  Calorimeter.  —  It  is  now  evident  that  if  a  definitely 
measurable  quantity  of  heat  could  be  added  to  the  steam  before 
it  was  allowed  to  expand,  even  very  wet  steam  might  be  ac- 
curately measured  by  the  throttling  calorimeter.  This  is  seen 
at  once  when  we  analyze  the  total  heats  involved.  If  E0  be 
the  heat  units  added  to  each  pound  of  steam,  then  the  total 
heat  possessed  by  each  pound  of  steam  in  the  high  pressure  main 


THE  STEAM  CALORIMETER  AND  ITS  USE  91 

is  (XoL0  -f-  h0  +  !£<,)  heat  units  and  since  the  heat  in  each  pound 
of  steam  in  the  lower  chamber  is  Hs,  we  have,  since  no  heat 
escapes 

XoL0  +  h0  +  E0  =  Hs 

v  Hs   —    h0    —    EO  /0v 

.  .AO  =          — =—  (/; 

LlQ 

In  the  Thomas  electric  meter  an  electrical  mechanism  has  been 
invented  whereby  a  series  of  small  wires  electrically  heated  impart 
a  known  quantity  of  electrical  energy  to  the  steam.  This  elec- 
trical energy  dissipates  itself  as  heat  and  since  we  can  transfer 
electrical  units  into  heat  units  and  vice  versa,  a  ready  means  is 
provided  to  assist  the  throttling  calorimeter  in  doing  its  work  by 
adding  sufficient  heat  to  widen  the  range  of  the  throttling  process. 

Thus,  although  the  throttling  calorimeter  was  found  definitely 
limited  as  set  forth  above,  let  us  investigate  a  case  where  the 
electrical  calorimeter  may  be  used.  Let  us  assume  the  upper 
pressure  to  be  200  Ib.  per  sq.  in.  and  the  lower  pressure  15.0  Ib. 
per  sq.  in.  In  this  case  there  were  electrically  added  exactly 
40  B.t.u.  of  energy  and  the  temperature  of  superheat  ts  was  found 
to  be  233. 0°F.,  hence  from  the  steam  tables  we  find 

L°  =  843.2;  h0  =  354.9;  ta  =  233.0;  hence,  Hs=  1160.1 

.  x     _  H60.1  -  354.9  -  40 
843.2~ 

The  Separating  Calorimeter. — In  the  separating  calorimeter 
the  moisture  is  mechanically  separated  from  the  steam.  If  we 
know  the  total  amount  of  steam  passing  and  also  the  weight  of 
the  water  separated  from  the  steam,  it  is  of  course  an  easy  prob- 
lem to  compute  the  dryness  of  the  steam.  Thus,  if  Wi  is  the 
weight  of  water  separated  per  hour  in  the  calorimeter  and  TF2 
the  weight  of  dry  steam  passing  out  of  the  calorimeter  per  hour, 
we  have  by  inspection 

x          w*  m 

~  Wt  +  W* 

Hence,  if  a  separating  calorimeter  deposits  285  Ib.  of  water  per 
hour  and  if  10,000  Ib.  of  dry  saturated  steam  leave  the  calori- 
meter per  hour,  the  dryness  of  the  steam  is 

10,000 
Ao~  10,000  +  285" 


92 


FUEL  OIL  AND  STEAM  ENGINEERING 


There  are  many  principles  upon  which  the  separating  calori- 
meter may  operate.  There  are  two  forms,  however,  which  are 
more  usual  than  others.  In  one  instance  the  steam  mixture  is 
given  a  rotary  motion  in  its  journey  and  consequently  the  water 
particles  are  thrown  off  by  centrifugal  force  and  collect  in  a  drip 
below.  In  the  other  instance  the  stream  flow  receives  a  sudden 
reversal  in  direction.  As  dry  steam  easily  performs  this  feat 
and  water  insists  upon  continuing  its  former  direction  of  flow 
a  separation  is  thus  mechanically  effected. 


FIG.  55. — The  separating  calorimeter. 

In  this  type  of  separating  calorimeter  the  steam,  with  its  moisture  enters  from  the  steam 
main  at  6  and  is  forced  to  travel  downward  toward  3  at  a  high  velocity.  At  14,  however, 
the  direction  is  suddenly  reversed  upward  toward  7  and  later  passed  downward  through  4 
and  out  into  the  atmosphere  at  8.  When  the  sudden  reversal  takes  place  at  14,  the  moisture 
in  the  steam  collects  at  3  and  its  content  is  measured  on  the  gage  12.  The  steam  content, 
on  the  other  hand,  is  calculated  by  means  of  Napier's  formula  as  it  passes  through  the  ori- 
fice at  8  as  illustrated  in  the  text. 

This  type  of  instrument  is  not  as  accurate  as  the  throttling 
type,  as  it  does  not  get  all  the  moisture  out  of  the  steam.  When 
large  quantities  of  moisture  are  present,  however,  it  proves  use- 
ful in  taking  out  the  bulk  of  the  water  or  moisture  while  a  throt- 
tling calorimeter  connected  in  series  later  on  accurately  measures 
the  remaining  water  content  present.  Thus  by  such  a  method  of 
operation  any  degree  of  moisture  present  in  steam  is  easily  and 
accurately  measured. 

Correction  for  Steam  Used  by  Calorimeter. — In  a  great  many 
instances  the  total  weight  of  steam  passing  per  hour  through  the 


THE  STEAM  CALORIMETER  AND  ITS  USE  93 

steam  main  under  test  is  of  prime  importance.  Since  most  forms 
of  calorimeter  operate  by  diverting  a  portion  of  this  steam  out 
into  the  atmosphere,  it  becomes  necessary  to  have  some  quick 
and  ready  means  of  computing  the  quantity  of  steam  so  diverted. 
Many  years  ago  Napier  deduced  an  approximate  formula  for 
the  flow  of  steam  into  the  atmosphere  from  a  high  pressure  source. 
This  formula  is  well  within  the  degree  of  accuracy  required  for 
steam  diverted  through  the  calorimeter.  If  W  is  the  pounds  of 
steam  flowing  per  second,  p  the  pounds  of  pressure  per  square 
inch  exerted  by  the  steam  in  the  main,  and  a  the  area  of  the  orifice 
in  square  inches  through  which  the  steam  passes,  then 

W^  (4) 

The  Sampling  Nipple. — The  American  Society  of  Mechanical 
Engineers  recommends  a  sampling  nipple  made  of  one-half  inch 
iron  pipe  closed  at  the  inner  end  and  the  interior  portion  perfor- 
ated with  not  less  than  twenty  one-eighth  inch  holes  equally 
distributed  from  end  to  end  and  preferably  drilled  in  irregular 
or  spiral  rows  with  the  first  hole  not  less  than  one-half  inch  from 
the  wall  of  the  pipe.  The  failure  to  determine  an  average  sample 
of  the  steam  is  the  principal  source  of  error  in  steam  calorimeter 
determinations. 

Conclusions  on  Moisture  Measuring  Apparatus. — Summing 
up  the  arguments  of  this  chapter  we  see  that  for  comparatively 
small  quantities  of  moisture  present  in  steam,  the  throttling 
calorimeter  is  the  most  accurate  device  for  its  quantitative  de- 
termination. If,  however,  large  quantities  of  moisture  are  pres- 
ent, two  methods  present  themselves.  Either  we  must  first 
remove  the  major  portion  of  the  moisture  by  means  of  a  separat- 
ing calorimeter  and  later  determine  the  remaining  moisture  con- 
tent by  means  of  the  throttling  calorimeter,  or  we  must  add  a 
definite  quantity  of  heat  to  the  original  steam  supply  by  means  of 
a  device  such  as  the  Thomas  Electric  calorimeter  and  then  deter- 
mine with  proper  computation  factors  the  moisture  present  by 
means  of  the  throttling  calorimeter. 

As  already  shown  the  throttling  calorimeter  may  be  used  up  to 
moisture  of  4  per  cent,  for  steam  at  100  Ib.  pressure  and  up  to  a 
little  over  5  per  cent,  for  steam  at  200  Ib.  pressure.  Most  boilers 
deliver  steam  containing  not  more  than  1J^  Per  cent,  or  2  per 
cent,  of  moisture  so  that  for  nearly  all  ordinary  work  the  throt- 


94 


FUEL  OIL  AND  STEAM  ENGINEERING 


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( 

S 

tling  calorimeter  has  sufficient  range,  and  owing  to  its  great  simpli- 
city and  remarkable  accuracy  it  is  almost  universally  used.  It 
is  possible  to  make  up  a  throttling  calorimeter  by  means  of  pipe 
fittings  by  providing  a  disc  within  a  pair  of  flanges  having  a 

small  hole  to  act  as  the  throttling 
agent,  as  shown  in  Fig.  54;  or  the 
throttling  may  be  done  merely  by 
partially  opening  the  valve  on  the 
sampling  nipple  close  to  the  main 
steam  pipe.  An  extremely  con- 
venient design  of  calorimeter  and 
one  that  can  be  readily  moved 
from  place  to  place  is  shown  in 
Fig.  56.  A  calorimeter  of  this 
type  should  have  a  deep  ther- 
mometer well,  C,  so  that  the  ther- 
mometer bulb  will  come  well  below 
the  steam  inlet  A,  thus  giving  the 
steam  a  chance  to  expand  to  the 
lower  pressure  before  its  tempera- 
ture is  taken.  In  this  design  a 
steam  jacket  is  provided  to  pre- 

FIG.  56.— A  suggestion  for  a  con-    vent,  as  far  as  possible  radiation 

losses  from  the  calorimeter.  For 
many  further  useful  pointers  and 
detail  rules  in  ascertaining  the  moisture  content  of  steam  the 
reader  is  referred  to  the  latest  edition  of  " Steam"  by  the  Babcock 
and  Wilcox  Company,  and  to  the  report  of  the  Power  Test  Com- 
mittee of  the  American  Society  of  Mechanical  Engineers  which  is 
to  be  found  in  Vol.  37,  transactions  A.  S.  M.  E.  for  1915,  to  which 
publications  we  are  indebted  for  much  of  the  information  con- 
tained in  this  discussion. 


SECTION  E-F 


venient  and  compact  type  of  throt 
tling  calorimeter. 


CHAPTER  XII 

RATIONAL   AND   EMPIRICAL   FORMULAS   FOR    STEAM 

CONSTANTS 

It  has  hitherto  been  pointed  out  that  the  relationships  of 
temperature,  latent  heat  and  other  steam  properties  are  so  com- 
plicated with  varying  pressures  that  no  one  as  yet  has  been  able 
to  set  forth  simple  mathematical  equations  for  their 
representation. 

There  exist,  however,  a  vast  number  of  more  or  less  complicated 
formulas  that  express  with  some  degree  of  accuracy  a  relationship 
between  these  various  factors.  When  such  a  relationship  is 
deduced  from  some  process  of  reasoning  based  upon  known  laws 
the  equation  is  said  to  be  rational.  If,  on  the  other  hand,  some 
one  by  sifting  through  the  sands  of  time,  as  it  were,  has  happened 
upon  an  equation  with  no  rational  backing  the  formula  is  said  to 
be  empirical. 

Most  of  the  equations  used  to  set  forth  steam  variables  are 
partly  rational  and  partly  empirical. 

Any  equation,  unless  it  be  comparatively  simple,  is  of  little 
practical  use  to  the  steam  engineer,  for  he  may  pick  the  values 
desired  from  the  modern  steam  tables  with  such  facility  that  it  is 
really  burdensome  to  try  and  remember  any  formulas  connecting 
these  properties. 

The  Value  of  Formulas  in  Steam  Engineering. — In  certain 
theoretical  reasoning,  however,  a  formula  setting  forth  these 
relationships  becomes  often  of  inestimable  value  and  indeed  at 
times  leads  one  to  attain  data  otherwise  impossible  to  compute. 
Such  is  the  case  of  the  formula  from  which  the  specific  volume 
of  saturated  steam  is  obtained  by  computation  and  set  forth  in 
Chapter  VII.  Here  it  is  found  impossible  to, obtain  by  experi- 
ment that  which  is  easily  computed  by  application  of  this  formula. 

We  shall  next  set  forth  some  of  the  comparatively  simpler 
relationships  or  equations  that  have  been  devised  or  annunciated 
by  various  authors.  These  will  serve  to  give  the  student  an 
insight  only  into  such  complicated  formulas  that  arise  in  attempt- 
ing a  mathematical  expression  for  these  data. 

95 


96  FUEL  OIL  AND  STEAM  ENGINEERING 

Unless  one  desires  to  go  deep  into  the  theoretical  discussions 
of  vapors  and  superheated  gases  such  a  brief  introduction  is 
nevertheless  fully  sufficient  for  the  mastering  of  most  problems 
in  steam  engineering  computation. 

Relation  Between  Temperature  and  Pressure  of  Saturated 
Steam. — It  has  already  been  set  forth  that  water  boils  or  that 
saturated  steam  begins  to  be  formed  from  water  at  different 
temperatures  for  each  variation  in  pressure.  No  one  as  yet  has 
set  forth  a  simple  rational  formula  connecting  this  relationship. 
In  the  issue  of  Power  of  March  18,  1910,  is  to  be  found  a  formula 
which  is  the  simplest  and  yet  one  of  the  most  accurate  empirical 
relations  yet  established.  This  formula  connects  the  temperature 
in  Fahrenheit  degrees  with  the  pressure  in  pounds  per  sq.  in.  at 
which  water  boils,  and  is  as  follows: 

t  =  200p*  -  101  (1) 

For  a  pressure  of  10  Ib.  per  sq.  in.  the  error  is  but  0.28  per 
cent.,  while  for  300  Ib.  per  sq.  in.,  it  becomes  but  0.32  per  cent. 
The  intermediate  values  are  far  less  in  error,  so  that  this  formula 
has,  indeed,  a  wide  range  of  usefulness. 

The  Total  Heat  of  Saturated  Steam. — Almost  a  century  ago 
Regnault  gave  to  the  world  his  celebrated  data  on  steam  engi- 
neering. So  accurately  and  so  carefully  did  he  perform  his  work 
that  even  today  his  experimental  results  are  used  in  steam  en- 
gineering computation,  although  of  course  corrections  are  applied 
where  certain  constants  involved  in  computation  are  now  known 
to  have  different  values. 

Regnault's  Formula. — Regnault's  formula  for  the  total  heat  Ht 
of  saturated  steam  at  temperature  t  is  one  of  the  simplest  ever 
invented  and  is  as  follows : 

Ht  =  1091.7  +  0.305(Z  -  32)  (2) 

Let  us  test  this  formula  by  comparing  its  results  with  those  set 
forth  in  the  steam  tables  for  235°F. 
Regnault's  Formula: 

#235  =  1091.7  +  0.305(235  -  32)  =  1153.6  B.t.u. 
From  Steam  tables: 

#235  =  1158.7  B.t.u. 

1158.7  -  1153.6  v  nAAo? 

.  •  .  Error  =  -     ~Tl58  7  X  100  =  0.44% 


FORMULAS  FOR  STEAM  CONSTANTS  97 

Hence  we  see  that  for  low  temperatures  the  error  involved  by 
using  the  classic  equation  of  Regnault  is  less  than  one-half  of  one 
per  cent. 

Henning's  Formula.  —  Marks  and  Davis  have  in  the  rear  of 
their  steam  tables  set  forth  a  formula  of  Henning,  which  though 
somewhat  more  complicated  than  Regnault's  is,  however,  very 
accurate.  This  formula  may  be  expressed  as  follows: 

Ht  =  1150.3  +  0.3745  (t  -  212)  -  0.000550 

(t  -  212)  2  (3) 

Let  us  now  test  the  accuracy  of  this  formula  by  substituting  the 
same  temperature  of  235°F.  as  used  in  Regnault  's  formula. 
By  Henning's  formula: 

#235  =  1150.3  +  0.3745  (235  -  212)  -  0.000550 
(235  -  212)2  =  1158.64  B.t.u. 

From  steam  tables: 

#235   =    H58.7. 


,  .  Error  =  X  100  =  0.0052% 

llOo.  / 

Hence  the  error  involved  in  the  use  of  this  formula  is  seen  to  be 
extremely  slight. 

Latent  Heat  of  Evaporation.'  —  Thiesen,  after  observing  certain 
limits  toward  which  the  latent  heat  of  evaporation  seemed  to 
tend,  suggested  the  following  formula  for  the  latent  heat  of 
evaporation  of  water: 

Lt  =  138.81    (689  -  0°'315  (4) 

Let  us  compare  this  with  the  steam  table  data  for  a  temperature 
of  235°F. 
Thiesen's  formula: 

L28B  =  138.81(689  -  235)  °'315  =  953.7. 
Steam  tables: 

L235  =  955.4 


.-  .  Error  =  r  X  100  =  0.178% 

955.4 

While  the  error  here  found  is  comparatively  small,  at  higher 
temperatures  this  error  becomes  excessive.  Hence  we  should 
apply  this  formula  with  due  regard  to  its  limitations. 

A  Second  Formula  for  Heat  of  Evaporation.  —  Students  in  the 
classes  of  mechanical  engineering  at  the  University  of  California 


98  FUEL  OIL  AND  STEAM  ENGINEERING 

have  established  a  relationship  for  latent  heat  and  temperature 
as  follows : 

L2  =  1209423  -  1289.5*  (5) 

This  formula  is  simple  and  yet  accurate  to  within  one-third 
of  one  per  cent,  for  a  wide  range  of  temperatures  of  from  100°F. 
to  350°F.  and  within  three-fourths  of  one  per  cent,  for  practically 
the  entire  range  involved  in  steam  engineering  practice.  The 
constants  set  forth  were  obtained  by  the  method  of  Least  Squares. 

Relationship  of  Specific  Volume  for  Superheated  Steam. — In 
the  chapter  on  The  Elementary  Laws  of  Thermodynamics, 
it  was  shown  that  the  pressure,  volume,  and  absolute  temperature 
of  a  perfect  gas  are  connected  by  a  very  simple  relationship  as 
set  forth  in  the  composite  formula  given  in  equation  (5)  on  page 
46.  Indeed,  it  was  shown  that  while  superheated  steam  is  not 
a  perfect  gas,  still  for  approximate  results  this  equation  may  be 
used. 

For  accurate  work,  however,  the  equation  of  Linde  is  found 
quite  satisfactory  although  exceedingly  cumbersome  in  its 
application.  This  equation  connects  the  pressure  p  in  pounds 
per  sq.  in.  and  specific  volume  v  in  cu.  ft.  per  pound  with  the 
absolute  temperature  T  in  the  following  relationship: 

pv  =  0.596277  -  p(l  +  0.0014p) 

[™*JS™  -  0.0833]    ;:  (6) 

To  illustrate  the  application  of  this  formula,  let  us  endeavor 
to  find  the  specific  volume  of  superheated  steam  at  526. 8°F. 
used  in  a  turbine  test  when  the  steam  was  under  a  pressure  of 
187.2  Ib.  per  sq.  in.  absolute. 

It  is  seen  that  the  absolute  temperature  of  the  superheated 
steam  was 

T  =  526.8  +  459.6  =  986.4 

and  since  the  absolute  pressure  p  was  187.2  Ib.  per  sq.  in.,  we 
have  by  substitution  in  the  formula 

v  =  3.05 
From  steam  tables: 

v  =  3.05 

Hence  in  this  instance  the  formula  appears  to  be  absolutely 
accurate  for  the  range  of  units  involved  in  the  steam  tables. 


FORMULAS  FOR  STEAM  CONSTANTS  99 

A  Simplified  but  Limited  Formula. — A  convenient  formula 
for  a  pressure  of  175  Ib.  per  sq.  in.,  the  approximate  pressure 
involved  in  steam  turbine  operations,  has  been  worked  out  by 
the  mechanical  engineering  students  at  the  University  of  Califor- 
nia for  superheat  between  fifty  and  six  hundred  .degrees  and  is  as 
follows : 

v  =  2.67  +  0.00377k  (7) 

Wherein  ts  is  the  number  of  degrees  superheat.  The  accuracy 
of  this  formula  is  within  one-half  of  one  per  cent,  for  the  range  of 
superheat  above  set  forth. 

Other  Relationships  Exists — By  making  use  of  certain  theoretic 
considerations  in  thermodynamics  many  other  equations  might 
be  written  setting  forth  still  other  relationships  involved  in  the 
determination  of  steam  constants,  but  sufficient  illustrations 
have  now  been  given  the  reader  for  a  thorough  introduction  to 
such  formulas.  Perhaps  after  all  the  most  important  lesson  one 
derives  from  their  use  is  that  their  application  is  often  so  tedious 
and  their  range  of  accuracy  often  so  questionable,  that  one  had 
better  stay  on  well  trodden  paths  and  master  to  their  fullest 
extent  the  application  of  the  steam  tables  and  diagrams  in  "the 
solution  of  all  steam  engineering  problems. 


CHAPTER  XIII 


THE  FUNDAMENTALS  OF  FURNACE  OPERATION  IN  FUEL 
OIL  PRACTICE 

'ANY  of  us  are  familiar  with  the 
famous  painting  that  pictures 
James  Watt  as  a  boy  gazing  in 
wide-eyed  amazement  at  the 
homely  tea-kettle  spouting  forth 
its  hitherto  unharnessed  power 
generating  vapors.  The  eyes  of 
the  youth  are  illuminated  with  that 
strange  and  wonderful  light  that  set 
forth  in  a  measure  some  of  the 
dreams  of  constructive  imagination 
which  must  have  been  filling  his 
consciousness  at  that  time. 

The  great  inventor  of  the  steam 
engine  undoubtedly  saw  in  the  tea- 
kettle before  him,  not  the  homely 
object  of  the  kitchen,  but  in  its 
expanded  form  one  of  the  most 
necessary  mechanisms  for  modern 
industrial  development — namely, 
the  steam  boiler. 

Let  us  then  examine  the  fundamental  operation  and  construc- 
tion of  the  steam  boiler,  and  consider  this  great  giant  of  modern 
industrial  aggrandizement  to  see  wherein  it  varies  from  its  pro- 
genitor— the  homely  tea-kettle  of  Watt's  boyhood  dream. 

The  Fundamentals  of  the  Tea-Kettle  and  the  Boiler  are  the 
Same. — The  tea-kettle  in  its  construction  and  operation  may  be 
considered  under  three  separate  discussions.  First,  there  must 
be  some  means  of  generating  and  imparting  heat;  secondly,  a 
container  for  the  water  and  steam  must  be  constructed  with 
physical  characteristics  to  meet  the  stresses  and  strains  involved ; 

100 


FIG.  57. — Air  ducts  for  furnace 
floor. 


.  FURNACE  OPERATION  IN  FUEL  OIL  PRACTICE        101 

and,  thirdly,  the  cycle  of  physical  operations  through  which 
the  water  and  steam  pass  in  the  generation  of  steam  is  of  vast 
importance. 

The  tea-kettle  operation  in  its  simplest  analysis  consists  of  a 
flame  placed  beneath  a  metal  container.  This  metal  container 
absorbs  the  heat  from  the  flame  and  transmits  it  to  the  water 
within  the  container.  When  sufficient  heat  has  been  absorbed 
by  the  water  within  the  container  to  raise  its  temperature  to  the 
boiling  point  corresponding  to  the  external  pressure  of  the  atmos- 


FIG.  58. — Boiler  installation  at  the  Long  Beach  Plant  of  the  Southern  California 
Edison  Company  under  construction. 

phere,  the  tea-kettle  boils  or  in  the  language  of  the  steam  engi- 
neer the  tea-kettle  generates  steam. 

In  its  fundamental  makeup,  the  boiler  too,  quite  closely  fol- 
lows this  familiar  and  homely  object — the  tea-kettle.  For  in 
the  modern  boiler  heat  is  first  generated  in  a  furnace.  This  heat 
is  then  imparted  to  a  metallic  drum  or  tubes  through  which  water 
is  passed.  When  sufficient  heat  is  thus  imparted  to  raise  the 
temperature  of  the  water  to  the  boiling  point  for  the  pressure 
involved,  steam  generation  takes  place. 


102 


FUEL  OIL  AND  STEAM  ENGINEERING 


Inefficiency  of  Tea  Kettle  Operation.  —  In  modern  kitchen 
economics  but  little  attention  is  paid  to  the  manner  in  which  the 
heat  is  imparted  to  the  tea-kettle.  Usually  the  stove  lid  is  taken 
off  and  the  kettle  placed  over  the  fire  space  thus  created.  Some 
minutes  later,  the  house-wife,  ignorant  of  the  vast  heat  losses 
that  have  taken  place,  returns  to  draw  off  the  hot  water  thus 
inefficiently  obtained  as  convenience  may  require.  As  a  matter 
of  fact,  the  slightest  and  most  casual  investigation  shows  that 
in  the  United  States  millions  of  dollars  are  wasted  every  year  for 


FIG.  59. — Same  view  of  boiler  plant  when  completed,  showing  auxiliary  appa- 
ratus and  steam  piping. 

lack  of  reasonable  care  in  the  kettle  operation.  This  loss  is, 
however,  so  widely  distributed  over  thousands  of  homes  that  it  is 
not  felt  in  any  concentrated  form. 

Efficiency  in  the  Modern  Steam  Boiler  a  Necessity. — In  the 
case  of  the  modern  central  station,  however,  efficiency  is  the  cry 
of  the  day.  For  with  competition  on  all  sides  and  regulating 
commissions  to  limit  the  prices  charged  for  the  power  supply, 
the  utmost  in  economic  steam  generation  is  essential. 

Hence,   in   modern   steam   boiler  operation,  especially  in  its 


FURNACE  OPERATION  IN  FUEL  OIL  PRACTICE        103 

heat  generating  properties,  a  wide  variation  from  tea-kettle 
operation  is  in  vogue,  not  so  much  in  fundamental  principles 
involved  as  in  efficiency  of  methods  employed  in  the  heat  generat- 
ing mechanisms 

Efficient  Furnace  Construction  of  Utmost  Importance. — To 
accomplish  this  efficiency  an  enclosed  compartment  beneath  the 
boiler  proper  is  built.  This  is  known  as  the  furnace.  In  this 
furnace  heat  generating  substances  such  as  coal,  wood,  and  crude 
petroleum  are  burned.  In  the  study  of  chemistry  it  has  been 
found  that  certain  primary  elements,  notably  carbon,  hydrogen, 


FIG.  60. — Typical  boiler  front  in  fuel  oil  practice. 

In  this  illustration  may  be  seen  the  fuel  oil  atomizer  in  the  ash  pit  entrance,  the  covered 
steam  pipes  for  supplying  steam  used  in  atomization,  the  fuel  oil  supply  pipes,  the  damper 
control,  the  draft  gage  and  other  accessories  for  fuel  oil  operation. 

and  sulphur,  upon  coming  in  contact  with  heated  oxygen  under- 
go a  chemical  reaction  and  in  doing  so  give  out  enormous  quan- 
tities of  heat.  It  is  the  generation  of  this  heat  and  its  ultimate 
absorption  by  the  water  in  the  boiler  that  makes  the  modern 
steam  engine  and  steam  turbine  the  giants  in  commercial  enter- 
prise that  today  they  represent. 

Fuels  Defined. — In  nature,  substances  such  as  coal,  wood  and 
crude  petroleum  are  found  in  vast  quantities  and  since  these 
contain  large  amounts  of  free  carbon  and  hydrogen,  they  make 
excellent  articles  for  heat  generation  and  are  called  fuels. 

An  Air  Supply  Essential. — It  has  been  mentioned  that  a  supply 
of  oxygen  is  absolutely  necessary  so  that  a  chemical  reaction 


104  FUEL  OIL  AND  STEAM  ENGINEERING 

may  take  place  and  thus  liberate  the  heat  held  in  suspense  in  the 
fuel.  The  air  about  us  is  made  up  of  about  20  per  cent,  oxygen 
and  80  per  cent,  nitrogen.  The  nitrogen  is  an  inert,  valueless 
ingredient  that  must  pass  into  the  furnace,  absorb  some  of  its 
heat  a'nd  go  out  through  the  chimney,  thus  conducting  away  into 
the  outer  atmosphere  some  of  the  heat  generated.  The  oxygen, 
however,  upon  coming  in  contact  with  the  heated  carbon,  hydro- 
gen and  sulphur  of  the  fuel,  readily  chemically  reacts  with  them. 

Enormous  quantities  of  heat  are  thus  liberated,  later  to  be  ab- 
sorbed by  the  water  of  the  boiler,  eventually  to  produce  the  steam 
delivered  for  the  driving  of  the  steam  engine  or  the  steam  turbine. 

Furnace  Operation. — Since  this  series  of  articles  is  largely  con- 
cerned with  fuel  oil  practice,  let  us  briefly  outline  the  furnace 
operation  for  such  practice.  In  a  later  chapter  this  will  be  taken 
up  in  more  detail. 

The  Fuel  Oil  Burner  and  Its  Function. — The  fuel  oil  is  sprayed 
into  the  furnace  by  means  of  an  atomizer  or  burner  which  pulver- 
izes the  oil  and  delivers  it  in  a  gaseous  vapor  or  in  small  globules 
at  the  hottest  place  in  the  furnace.  Air  is  admitted  from  below 
and  as  soon  as  the  temperature  is  raised  to  the  ignition  point 
chemical  reaction  takes  place  with  the  atomized  fuel  oil,  and 
thus  heat  is  generated.  This  heat  is  absorbed  by  the  gases  of  the 
furnace  and  consequently  their  temperature  is  at  once  raised 
often  times  to  2300°  or  2500°F.  These  furnace  gases  consist  of 
the  inert  nitrogen  that  partly  constituted  the  entering  air,  the 
carbon  dioxide  or  carbon  monoxide  formed  by  the  burning  of 
the  carbon,  water  vapor  formed  by  the  burning  of  the  hydrogen, 
sulphur  dioxide  formed  by  the  burning  of  the  sulphur  content, 
which  latter  ingredient  is  always  small,  and  a  considerable 
quantity  of  free  oxygen  depending  on  the  amount  of  excess  air 
admitted  to  the  furnace. 

The  Path  of  the  Furnace  Gases. — In  their  expanded  condition, 
due  to  the  absorption  of  such  huge  quantities  of  heat,  the  gases 
now  travel  upward.  As  they  come  in  contact  with  the  boiler 
drums  or  tubes  through  which  water  is  circulating,  the  gases  are, 
of  course,  cooled  and  the  temperature  of  the  water  raised.  In 
this  maner  the  gases,  having  been  chilled  or  lowered  in  tempera- 
ture to  500  deg.  or  600  deg.  F.,  are  finally  passed  up  through  the 
chimney,  and  steam  generation  within  the  boiler  is  accomplished. 

The  Economizer  and  Its  Economic  Value. — In  some  boiler 
installations  a  series  of  tubes  through  which  cold  water  is  passing, 


FURNACE  OPERATION  IN  FUEL  OIL  PRACTICE        105 

is  placed  between  the  boiler  and  the  chimney.  The  chimney 
gases  are  thus  forced  to  give  up  still  more  of  their  heat.  These 
outgoing  chimney  gases  are  consequently  reduced  still  further  in 
temperature. 

Such  a  device  as  cited  above,  is  known  as  an  economizer. 
This  reduction  in  the  temperature  of  the  out-going  chimney 
gases  reduces  the  draft  of  the  chimney.  Hence,  the  economizer 
is  an  economic  success  so  long  as  the  saving  in  feed-water  heating 
is  greater  than  the  interest  on  the  cost  of  the  economizer  installa- 
tion and  other  apparatus  necessary  to  produce  artificial  draft, 
plus  the  cost  of  maintenance  of  this  additional  apparatus. 

Quantity  of  Air  Required. — It  has  been  observed  that  the 
entrance  of  air  into  the  furnace  is  absolutely  essential  for  furnace 
operations.  Too  much  air,  however,  is  detrimental,  for  more 
oxygen  may  be  admitted  than  can  be  economically  used  by  the 
fuel.  Hence,  too  great  an  excess  of  air  simply  means  the  passage 
up  through  the  chimney  of  excess  gases  which  absorb  heat  only 
to  convey  it  out  into  the  atmosphere  without  performing  a  useful 
function.  In  successful  boiler  operation,  therefore,  some  means 
must  be  provided,  first  to  measure  the  draft;  second,  to  test  the 
ingredients  of  the  outgoing  gases;  and  third,  to  regulate  the 
entrance  of  air  into  the  furnace. 

The  Draft  Gage  and  Its  Principle  of  Operation. — A  draft  gage 
usually  consists  of  a  column  of  water  placed  in  a  U-tube.  The 


FIG.  61.— The  differential  draft  gage. 

In  order  to  exaggerate  the  readings  of  the  draft  in  inches  of  water,  the  measuring  tube 
rests  on  a  slope  of  ten  to  one  in  this  type  of  instrument,  and  thus  readings  to  another  decimal 
point  are  ascertained  which  would  otherwise  be  impossible. 


pressure  in  the  chimney  is  less  than  the  atmosphere  without. 
Therefore,  if  one  end  of  this  tube  is  inserted  into  the  chimney 
and  the  other  rests  under  the  atmospheric  pressure  without,  the 
difference  of  water  level  thus  obtained  in  the  U-tube  indicates 
the  draft  in  inches  of  water.  This  may  be  converted  into  pounds 


106  FUEL  OIL  AND  STEAM  ENGINEERING 

pressure  (absolute)  per  square  inch  by  applying  the  formulas 
previously  set  forth  in  the  chapter  on  pressures. 

Apparatus  for  Determining  Ingredients  of  Out-Going  Chimney 
Gases. — For  economic  boiler  operation  the  steam  engineer  should 
know  the  exact  composition  of  the  outgoing  chimney  gases. 
Since  this  is  a  matter  of  vast  importance  a  later  chapter  will  be 
given  in  which  detailed  discussions  of  methods  involved  and 
apparatus  employed  will  be  given.  Suffice  it  to  say  at  this  point, 
however,  that  by  means  of  such  apparatus  the  engineer  may 
determine  whether  the  fuel  is  being  properly  consumed  in  the 
furnace  and  whether  too  little  or  too  much  air  is  being  admitted 
into  the  furnace. 

Draft  Regulating  Devices. — In  fuel  oil  practice  the  proper  sup- 
ply of  air  may  be  determined  to  a  nicety.  Hence  some  means 
must  be  provided  to  regulate  the  air  supply  with  the  same  pre- 
cision. This  is  done  by  varying  the  amount  of  opening  of  either 
the  ash  pit  doors  or  the  boiler  damper  or  both.  If  the  air  is 
regulated  by  partly  closing  the  ash  pit  doors  and  leaving  the 
damper  wide  open  a  strong  draft  may  occur  inside  the  boiler 
setting  which  tends  to  draw  air  in  through  the  brick  walls.  As 
this  is  a  detriment  it  is  preferable  to  regulate  the  air  by  means  of 
the  damper. 

The  Chimney. — After  the  gases  have  passed  through  and 
around  the  various  heat  absorbing  tubes  and  drums  employed 
in  the  modern  steam  boiler  and  economizer,  they  are  shot  up 
into  the  atmosphere  through  a  long  vertical  passage.  The 
structure  housing  this  passage  is  known  as  a  chimney.  The 
height  of  the  chimney  and  its  area  of  cross-section  through  which 
the  flue  gases  pass  have  an  important  bearing  on  the  economic 
boiler  or  rather  furnace  operation. 

In  a  general  way,  the  reader  now  has  a  grasp  of  the  funda- 
mentals involved  in  modern  furnace  operation  for  the  steam 
boiler.  We  shall  next  consider  the  container  or  shell  for  steam 
generation  and  its  accessories. 


CHAPTER  XIV 


THE  BOILER  SHELL  AND  ITS  ACCESSORIES  FOR  STEAM 
GENERATION  IN  FUEL  OIL  PRACTICE 

1ET  us  now  consider  some  of  the 
fundamental  laws  involved  in  heat 
transference,  and  then  discuss  the 
container  or  shell  employed  in 
steam  generation  together  with  the 
accessories  that  must  accompany 
any  high  pressure  steam  gener- 
ating unit  to  accomplish  safe  and 
efficient  operation. 

Going  back  once  again  to  the 
homely  tea-kettle  for  a  simple 
illustration,  we  find  that  the  con- 
tainer for  the  water  and  steam 
usually  consists  of  a  flat  bottomed 
metallic  vessel  with  free  opening  to 
allow  the  steam  generated  to  escape 
FIG.  62.-The  clean,  clear  cut  to  the  atmosphere.  There  is  also 

appearance  of  the  oil  fired  boiler    usually    to    be    found    an    Opening 

with  a  lid  covering  at  the  top 

where  water  may  be  passed  in  or  the  vessel  cleaned  at  more  or 
less  irregular  periods  of  operation  in  household  economics. 

In  the  case  of  the  steam  boiler,  however,  vast  improvements 
in  physical  configuration  and  construction  become  a  necessity. 
Let  us  then  examine  some  of  these  differences. 

The  Laws  of  Heat  Involved  in  Steam  Generation. — The 
transference  of  heat  is  found  by  experimental  observation  to 
take  place  in  three  separate  and  distinct  ways — namely,  by 
conduction,  by  radiation,  and  by  convection. 

On  a  wintry  night  if  one  stands  in  front  of  a  blazing  fireplace 
it  is  easy  to  find  illustrations  of  these  three  methods  of  heat 
transference.  Thus  standing,  one  feels  the  heat  radiating  to  his 
face  in  outward  projections  from  the  fire,  for  if  an  article  such 

107 


108  FUEL  OIL  AND  STEAM  ENGINEERING 

as  a  solid  screen,  opaque  to  heat  radiation,  be  placed  between 
the  face  and  the  fire  the  sensation  of  heat  on  the  face  immediately 
disappears.  If  now  from  behind  the  screen  one  holds  a  metallic 
poker  in  the  hot  fire,  it  will  not  be  long  before  the  poker  even  at 


FIG.  63. — Front  view  of  new  boiler  installation. 

In  this  view  may  be  seen  the  pit  and  foundation  setting  for  oil  furnace  in  the  new  addi- 
tional installation  recently  put  in  by  the  Pacific  Gas  and  Electric  Company,  San  Francisco. 
Note  the  clean  trim  appearance  extending  to  the  older  fuel  oil  installation  on  the  extreme 
left,  which  is  quite  characteristic  of  boiler  rooms  where  oil  is  used  as  fuel. 

the  point  behind  the  screen  becomes  so  hot  by  conduction  that  it 
cannot  comfortably  be  held  in  the  hand.  And  finally  should 
a  sudden  gust  of  wind  blow  down  the  chimney  a  hot  gust  of  air 


THE  BOILER  SHELL  AND  ITS  ACCESSORIES  109 

may  be  driven  out  into  the  room  and  around  the  screen  to  the 
observer's  face,  thus  illustrating  the  transference  of  heat  by 
convection. 

The  Principle  of  Operation  of  the  Steam  Boiler.  —  Let  us  then 
see  how  these  three  methods  of  heat  transfer  are  utilized  in 
modern  boiler  operation. 

As  has  been  previously  noted,  the  burning  of  the  fuel  in  the 
furnace  causes  enormous  quantities  of  heat  to  be  given  out  in  the 
furnace  space.  This  heat  is  immediately  absorbed  by  the  fur- 
nace gases,  thereby  raising  them  to  a  high  temperature.  By 
convection  currents,  and  also  by  radiation,  this  heat  is  now  trans- 
ferred to  the  outer  surface  of  the  boiler  shell  and  tubes  containing 
the  water  that  it  is  desired  to  convert  into  steam.  The  metallic 
shell  and  water  tubes  having  now  absorbed  the  heat,  convey  it 
to  their  inner  surface  by  conduction  where  it  is  transferred  to  the 
water  in  the  boiler.  This  water,  becoming  heated,  expands, 
and  due  to  its  lighter  density  thus  created  is  forced  to  go  to  the 
top  of  the  water  surface  to  make  way  for  cooler,  heavier  water 
which  in  turn  absorbs  heat  and  disappears  to  make  way  for  other 
water.  This  last  activity  is  evidently  again  transference  by 
convection  currents  and  such  a  movement  of  water  is  called 
circulation.  The  efficient  manner  in  which  this  circulation  takes 
place  has  much  to  do  with  the  economic  operation  of  the  boiler. 

Mathematical  Equation  for  Heat  Transfer.  —  In  1909  Dr. 
Wilhelm  Nusselt  of  Germany  devised  a  formula  whereby  the 
factors  involved  in  the  rate  of  transference  of  heat  are  set  forth 
quantitatively.  This  formula  reduced  to  English  units  by  the 
Babcock  and  Wilcox  Company  in  their  book  on  Steam  is  as 
follows  : 

X  (Wr  V7sr, 

_          f\  rvOCC         w  *  p'  /1\ 

•0.0255-  - 


Wherein  a  is  the  transfer  rate  in  B.t.u.  per  square  foot  of  surface 
per  degree  difference  in  temperature;  W  is  the  weight  of  pounds 
of  the  gas  flowing  through  the  tubes  per  hour;  A  is  the  area  of 
the  tube  in  square  feet,  d  is  the  diameter  of  the  tube  in  feet; 
cp  is  the  specific  heat  of  the  gas  at  constant  pressure;  X  is  the 
conductivity  of  the  gas  at  the  mean  temperature  and  pressure 
in  B.t.u.  per  hour  per  square  foot  of  surface  per  degree  Fahren- 
heit drop  in  temperature  per  foot;  and  X«,  is  the  conductivity 
of  the  steam  at  the  temperature  of  the  wall  of  the  tube, 


110  FUEL  OIL  AND  STEAM  ENGINEERING 

Mathematical  Law  for  Total  Heat  Absorption.  —  The  applica- 
tion of  this  formula  is  cumbersome  and  indeed  upon  careful 
analysis  it  is  seen  to  be  largely  empirical  in  its  nature.  Let  us 
then  cast  about  for  another  equation. 

Stefan's  law  sets  forth  that  the  heaL  absorbed  per  hour  by 
radiation  is  proportional  to  the  difference  of  the  fourth  powers  of 
the  absolute  temperature  of  the  furnace  gases  T  and  the  absolute 
temperature  of  the  tube  surface  t  of  the  boiler.  In  addition  to 
this  if  we  add  the  loss  of  heat  given  up  by  the  outgoing  gases 
due  to  their  cooling  from  the  absolute  temperature  TI  to  the 
absolute  temperature  T2  on  the  assumption  that  the  boiler 
tubes  have  absorbed  all  this  heat,  we  have  for  the  total  heat 
absorption  : 


*  -  160°  [  - 


In  which  E  is  the  total  evaporation  of  a  boiler  measured  in  B.t.u. 
per  hour,  Sl  is  the  area  of  boiler  surface,  W  is  the  weight  of  gas 
leaving  the  furnace  and  passing  through  the  setting  per  hour,  and 
C  is  the  specific  heat  of  the  gas. 

Relationship  of  Rate  of  Heat  Transfer.  —  By  means  of  the 
integral  calculus  it  may  now  be  found  from  the  above  equation 
that  the  rate  of  heat  transfer  R  may  be  expressed  by  the  equation 


This    law  shows  an  important  relationship  of  temperatures 

<  whereby  we  may  design  condenser  shells  as  well 
as  boiler  shells  to  accomplish  a  maximum  rate 
of  heat  transfer. 
In  the  Babcock  and  Wilcox  type  of  boiler  the 
constants  involved  in  heat  transference  have 
been  quite  accurately  ascertained.  By  sub- 
stituting these  constants  the  above  equation  is 
found  to  reduce  to  the  simple  relationship: 

FIG.  64.—  A  safety  p  W 

water  column.  «  =  2-00  -f  0.0014  j- 

Necessity  for  Boiler  Accessories.  —  Since  the  modern  boiler 
operates  under  pressures  and  temperatures  far  in  excess  of  the 
tea-kettle  and  since  the  quantities  of  water  involved  are  far 
beyond  hand  operation,  the  necessity  for  the  creation  of  acces- 


THE  BOILER  SHELL  AND  ITS  ACCESSORIES  111 

series  to  properly  care  for  these  increased  responsibilities  early 
became  apparent  in  the  evolution  of  steam  engineering. 

Injector  or  Pump  for  Feed  Water  Supply.— In  order  to  supply 
the  boiler  with  the  necessary  water  involved  in  steam  generation 
the  injector  has  made  its  appearance  in  some  instances,  while 
feed-water  pumps  are  used  in  other  instances. 

Since  the  modern  boiler  operates  at  from  100  to  275  Ib.  pres- 
sure per  square  inch,  it  is  evident  that  the  water  must  be  forced 
into  the  boiler,  for  no  ordinary  water  supply  is  obtainable  to  meet 
such  adverse  pressures. 


FIQ.  65. — Stop,  check  and  blow-off  valves. 

The  type  of  pump  most  frequently  met  with  for  boiler  feed 
purposes  is  the  ordinary  duplex  double  acting  pump  in  which 
the  steam  cylinder  is  made  larger  than  the  water  cylinder  to 
enable  the  water  to  be  forced  into  the  boiler  at  a  pressure  greater 
than  that  of  the  steam  itself.  Pumps  of  this  type  are  very  re- 
liable and  if  chosen  of  sufficient  size  so  they  can  be  operated  at 
slow  speed  give  excellent  satisfaction. 

For  large  power  plants  the  centrifugal  pump  is  coming  into 
favor  owing  to  the  small  space  it  occupies  and  the  small  attend- 
ance required.  It  is  built  in  four,  five  or  six  stages,  depending  on 
the  water  pressure  required,  and  may  be  driven  by  either  an 
electric  motor  or  a  small  steam  turbine. 

The  operation  of  the  injector  is  accomplished  by  drawing  a 
certain  amount  of  steam  from  the  boiler  and  allowing  it  to  attain 
an  enormous  velocity.  This  steam  then  comes  in  contact  with 
the  feed  water  supply  which  at  once  converts  this  impinging 
steam  into  water.  The  immense  impetus  of  the  outflowing 
steam  and  the  conversion  of  the  latent  energy  of  this  steam  into 
kinetic  energy  of  motion  causes  the  feed  water  to  be  sucked  in 
and  driven  against  the  check  valves  of  the  boiler  with  such  force 


112  FUEL  OIL  AND  STEAM  ENGINEERING 

as  to  overcome  the  opposing  pressure  and  allow  such  water  to 
enter  as  may  be  needed. 

The  injector  is  limited  in  its  field  of  operation  by  the  fact  that 
the  water  must  be  cold  enough  to  condense  the  injected  steam — 
in  other  words  the  injector  cannot  pump  hot  water.  As  the 
hotter  the  feed  water  the  more  economical  the  plant  the  injector 
is  only  suitable  in  plants  where  there  is  no  hot  water  available. 

, This  condition  exists  on  the  locomotive  where 

•  I    the  injector  finds  its  greatest  usefulness. 

Check  and  Non-Return  Valves. — In  order 

'   that  no  water  should  flow  back  out  through  the 

entrance  valve,  some  means  must  be  provided. 

Many  types   of  valve  are  used  in  practice  to 

^L  perform   this   function.     An   illustration   of   a 

typical  type  of  check  valve  is  shown  in  the 

picture  exhibited  herewith.     Fig.  65. 

The  Steam  Gage  and  the  Water  Gage.— In 
the  operation  of  the  tea-kettle  the  escaping  of 


FlG  66 siphon  the  steam  into  the  atmosphere  readily  pre- 

for  keeping  steam  vents  the  possibility  of  explosion,  and  the  ever 
watchful  eye  of  the  housewife  is  utilized  to  see 
to  it  that  the  water  supply  is  sufficient  for  safe  operation.  The 
use  of  high  pressures  and  inclosed  boiler  shells  makes  it  im- 
perative in  steam  engineering  to  have  some  means  of  ascertain- 
ing the  pressure  under  which  the  boiler  is  operating  and  to 
determine  the  height  of  the  water  in  the  boiler  shell.  The 
steam  gage  meets  the  former  requirement.  This  type  of  instru- 
ment was  described  in  the  chapter  on  pressures. 

To  ascertain  the  water  level  in  the  boiler  shell,  the  installa- 
tion of  water  columns  enclosed  in  glass  tubes  makes  visible  the 
height  of  the  water  in  the  boiler.  The  water  column  is  located 
so  that  its  center  is  at  about  the  proper  height  of  water  in  the 
boiler.  The  upper  end  of  the  column  is  connected  to  the  steam 
space  of  the  boiler  and  the  lower  end  to  the  water  space,  so  that 
the  water  in  the  column  always  rises  to  the  same  height  as  the 
water  in  the  boiler.  The  bottom  of  the  glass  must  be  a  little 
higher  than  the  lowest  level  at  which  it  is  safe  to  carry  the  water 
to  prevent  damage  by  overheating  the  sheets  or  tubes,  and  the 
top  of  the  glass  must  be  a  little  lower  than  the  level  at  which 
water  would  begin  to  be  lifted  and  carried  out  with  the  steam. 
Pet-cocks  are  provided  so  that  the  water  column  may  be  cleaned 


THE  BOILER  SHELL  AND  ITS  ACCESSORIES  113 

of  sediment  at  frequent  intervals  to  insure  its  safe  and  accurate 
operation.  Since  the  ascertaining  of  the  exact  water  height  in 
the  boiler  is  of  such  vast  importance,  three  additional  pet-cocks 
called  Gage  Cocks  are  usually  installed  near  the  water  glass.  One 
of  these  is  located  above  the  proper  water  level,  the  second  at 
about  the  water  level,  and  the  third  below  it.  Hence,  upon  trial 
if  the  boiler  is  properly  operating,  the  first  should  emit  colorless 
dry  saturated  steam,  the  second  water  vapor  and  the  third  hot 
water. 

Manholes. — To  clean  and  examine  the  boiler  interior  some 
means  must  be  provided  by  which  access  may  be  had  to  its  in- 
terior. On  all  modern  types  of  boilers  will  be  found  man-holes 
and  hand-holes  whereby  this  access  may  be  obtained  when  oc- 
casion arises. 

Provision  for  Expansion. — The  excessive  temperatures  under 
which  a  boiler  operates  and  the  sudden  change  from  one  tempera- 
ture to  another  make  it  absolutely  imperative  that  some  means 
be  provided  to  take  care  of  uneven  expansion  in  its  parts.  Most 
boilers  on  the  market  do  not  for  this  reason  allow  the  boiler  shell 
to  rest  upon  the  furnace  structure,  but  on  the  other  hand  the 
boiler  is  suspended  from  above  and  all  suspended  parts  are  al- 
lowed to  swing  free  with  ample  clearance  between  them  and  the 
brick-work.  The  care  with  which  uneven  expansion  and  its 
disastrous  results  are  provided  for  makes 
much  for  efficient  boiler  design. 

The  Mud  Drum. — Since  all  water  contains  a 
certain  amount  of  impurities,  some  space  must 
be  set.  aside  for  the  collection  and  segregation 
of  these  impurities.  Such  a  compartment  is 
known  as  the  mud  drum.  This  is  cleansed  at 
definite  periods  by  blowing  down  the  boiler, 
that  is  by  opening  the  blow-off  valve  at  the 
bottom  of  the  mud  drum  and  allowing  some 
of  the  water  to  escape  from  the  boiler  into  the  FIQ.  67.— Pop  safety 

T  valve. 

atmosphere. 

Safety  Valve. — All  boilers  are  definitely  standardized  so  that 
steam  generation  must  not  exceed  a  certain  pressure  develop- 
ment. To  prevent  this  excessive  generation  of  pressure  a  safety 
valve  is  always  installed.  These  are  in  general  of  two  types,  the 
one  having  its  outlet  to  the  outside  air  controlled  by  a  spring 
set  for  the  pressure  desired,  the  other  controlled  by  a  weight  and 


114  FUEL  OIL  AND  STEAM  ENGINEERING 

lever  arm  set  for  the  blow-off  pressure  desired.  Since  the  total 
pressure  required  to  open  the  valve  equals  its  area  in  square  inches 
times  the  pressure  in  pounds  per  square  inch  the  compression  in 
the  spring  or  the  weight  on  the  lever  may  be  determined  in  advance 
for  any  desired  pressure  in  the  boiler. 

Having  now  a  general  ground  work  of  boiler  shell  character- 
istics in  their  relation  to  heat  transfer,  and  bearing  in  mind  the 
accessories  that  must  accompany  the  modern  boiler,  we  shall 
next  consider  the  commercial  type  of  boiler  and  its  classification. 


CHAPTER  XV 
BOILER  CLASSIFICATION 

N  the  generation  of  steam  by  the 
tea-kettle  the  cycle  of  operations 
through  which  the  water  and  steam 
pass  is  quite  simple.  The  heat 
applied  at  the  bottom  of  the  tea- 
kettle is  absorbed  by  the  water 
along  its  surface  exposed  to  the 
heat  application.  As  this  heat  is 
absorbed  the  water  is  raised  in  tem- 
perature and  due  to  its  immediate 
expansion  becomes  lighter  than  the 
FIG.  68.— A  battery  of  fifteen  water  above  it  and  consequently 

boilers  oil-fired,  requiring  but  two  ,  _ 

men  for  their  operation.  passes    to    the    top    to    allow   cooler 

water  to  descend,  which   in  turn 

becomes  heated  and  passes  to  the  top  to  make  way  for  still 
other  water  to  become  heated.  This  cycle  of  operations  con- 
tinues and  finally  evaporation  takes  place.  The  steam  thus  gen- 
erated passes  to  the  atmosphere  without. 

In  the  modern  high  pressure  steam  boiler  the  operation  is  some- 
what more  complicated.  The  water  circulation  proceeds  on 
the  same  general  principle  but  since  steam  generation  is  the  im- 
portant function  and  not  merely  the  supplying  of  hot  water  as  in 
the  tea-kettle,  some  space  must  be  provided  wherein  to  store  the 
steam  that  is  generated.  This  is  usually  accomplished  in  the 
space  above  the  water  level  in  the  main  boiler  shell  or  drum. 
If  superheated  steam  is  to  be  produced,  the  saturated  steam  is 
conveyed  from  this  space  into  tubes  known  as  a  superheater. 
These  tubes  are  exposed  to  the  hot  furnace  gases  and  the  steam , 
passing  through  them  readily  absorbs  heat,  thus  super-heating 
the  saturated  steam  to  any  temperature  determined  upon. 

The  Boiler  Drum  and  Tubes. — It  has  been  mentioned  that 
the  tea-kettle  is  a  most  inefficient  boiler,  and  so  it  is.  While 
mechanical  stresses  and  strains  involved  necessitate  the  employ- 
ment of  cylindrical  shells  for  boilers,  still  the  boiler  itself  resem- 

115 


116 


FUEL  OIL  AND  STEAM  ENGINEERING 


bled  in  the  early  days  of  the  steam  engine  but  slight  variations 
from  the  tea-kettle. 

It  soon  became  apparent,  however,  that  the  actual  surface 
exposed  to  the  heated  gases  of  the  furnace  has  much  to  do  with 
efficient  steam  generation.  Hen.ce  while  the  first  type  of  boiler 
was  made  in  a  solid  shell,  variations  from  this  standard  soon 
made  their  appearance.  Let  us  now  examine  some  of  these  types. 

Internally  and  Externally  Fired  Boilers. — In  the  earlier  type 
of  boiler  the  fire  was  kindled  beneath  the  solid  cylindrical  boiler 
shell.  Such  a  type  became  known  as  an  externally  fired  boiler. 


FIG.  69. — A  Milwaukee  high  pressure  horizontal  tubular  boiler  with  full  front 
and  suspension  setting. 

Later  the  boiler  compartment  was  hollowed  out  and  the  fire 
kindled  inside  this  hollow  space,  thus  introducing  the  internally 
fired  type.  The  locomotive  boiler  is  today  an  illustration  of  this 
type  of  boiler. 

The  Return  Tubular  Boiler. — Another  type  soon  developed 
wherein  the  fire  was  kindled  beneath  and  the  flue  gases  returned 
to  the  front  part  of  the  boiler  through  a  series  of  flutings  or  tubes 
passing  through  the  main  part  of  the  boiler  shell.  Such  a  boiler 
became  known  as  a  return  flue  boiler  or  return  tubular  boiler 
depending  upon  whether  or  not  the  tubes  or  flutings  exceeded 
six  inches  in  diameter — the  flue  being  the  larger  diameter  and  the 
tube  the  smaller. 

The  Fire  Tube  and  the  Water  Tube  Boiler. — A  great  many 
types  of  boilers  finally  made  their  appearance  on  the  market  in 


BOILER  CLASSIFICATION  117 

some  of  which  the  fire  passed  through  the  tubes  which  were 
surrounded  by  water  in  the  boiler  shell,  and  in  other  instances 
the  water  passed  through  the  tubes  around  the  external  surface 
of  which  the  heated  gases  were  made  to  pass.  The  former  be- 
came known  as  fire  tube  while  the  latter  were  called  water  tube 
boilers.  It  is  generally  conceded  that  where  rapid  steaming  is 
required  the  latter  type  is  far  preferable. 

It  is  now  universally  the  custom  to  use  water  tube  boilers  in 
large  stationary  power  plants.  The  principal  reasons  are  the 
following : 

1.  Small  floor  space  required. 

2.  Greater  safety  at  high  pressures  due  to  the  small  diameter  of  the  drums 
and  tubes. 

3.  Greater  flexibility  so  that  expansion  strains  are  not  injurious. 

4.  Rapid  steaming  and  sudden  change  of  load  more  easily  accommodated. 

Tubular  boilers  still  have  their  field  in  small  one  man  plants, 
where  owing  to  the  large  quantity  of  water  contained  in  the 
shell  they  maintain  a  uniform  pressure  with  but  little  attention. 

Tubular  boilers  of  the  Scotch  marine  type  are  still  extensively 
employed  in  marine  work  where  owing  to  the  steadiness  of  the 
load  they  have  met  with  great  success. 

Vertical  and  Horizontal  Types. — Still  other  classifications  are 
made  based  upon  whether  the  tubes  and  boiler  shell  be  in  a 
horizontal  or  vertical  position,  the  former  being  called,  as  one 
would  presume,  the  horizontal  and  the  latter  the  vertical  type 
of  boiler.  As  time  went  on  still  other  boilers  appeared  which 
could  neither  be  called  horizontal  nor  vertical  but  an  intermediate 
classification  became  necessary. 

Let  us  now  examine  two  types  of  boiler  used  in  the  modern 
central  station  in  order  the  more  clearly  to  grasp  the  fundamentals 
of  boiler  design  and  principles  of  operation. 

Illustrations  of  Principles  of  Construction  and  Operation. — 
Before  proceeding  to  the  brief  description  of  these  two  types  of 
boiler,  the  reader  must  bear  in  mind  that  these  particular  two  are 
picked  as  best  setting  forth  principles  of  construction  and  opera- 
tion, and  not  necessarily  as  a  preference  for  commercial  installa- 
tion. Many  types  of  boiler  are  today  upon  the  market  and  in 
their  separate  and  distinctive  features  such  possess  characteristics 
that  must  be  carefully  considered  in  making  a  commercial  choice. 
With  this  understanding  let  us  then  proceed  to  examine  these 
two  boiler  types  of  commercial  practice. 


118  FUEL  OIL  AND  STEAM  ENGINEERING 

The  Babcock  and  Wilcox  Boiler. — By  a  close  examination  of 
the  illustration  shown  on  page  7,  the  Babcock  and  Wilcox  boiler 
is  seen  to  be  composed  of  one  or  more  horizontal  shells  or  drums 
from  which  are  suspended  a  series  of  inclined  tubes. 

In  this  type  of  boiler  installation  the  oil  burner  is  located  in  the 
rear  of  the  furnace  and  the  fuel  oil  is  shot  forward  toward  the 
front.  The  heated  gases  then  pass  upward  and  around  the 
tubes  through  what  is  known  as  the  first  pass.  At  the  top  of  this 
pass  the  heated  gases  envelop  the  lower  half  of  the  boiler  shell  and 
are  then  diverted  downward  through  and  around  the  superheater 
tubes  shown  immediately  below  the  drum  until  the  journey 
through  the  second  pass  is  completed.  At  the  rear  of  the  furnace 
wall  they  are  once  again  diverted  upward  through  the  third  pass 
and  then  after  contact  with  the  boiler  shell,  they  are  conveyed 
out  through  the  breeching  up  the  stack  or  chimney.  In  this 
manner  the  heated  gases  are  brought  into  intimate  contact  with 
the  water  tubes  and  efficient  steam  generation  accomplished. 

Water  Circulation. — The  water  for  steam  generating  purposes 
is  introduced  through  the  front  drumhead  of  the  boiler.  It 
then  passes  to  the  rear  of  the  drum,  downward  through  the 'rear 
circulating  tubes  to  the  sections.  Then  it  courses  upward  through 
the  tubes  of  the  sections  to  the  front  headers  and  through  these 
headers  and  front  circulating  tubes  again  to  the  drum  where  such 
water  as  has  not  been  formed  into  steam  retraces  its  course.  The 
steam  formed  in  the  passage  through  the  tubes  is  liberated  as  the 
water  reaches  the  front  of  the  drum.  The  steam  so  formed  is 
stored  in  the  steam  space  above  the  water  line. 

The  Parker  Boiler. — Another  type  of  boiler  which  is  exceed- 
ingly interesting,  as  its  operating  principles  are  almost  diametri- 
cally opposite  to  the  foregoing  is  that  of  the  Parker  boiler. 

As  seen  from  the  illustration  on  page  119,  the  fuel  oil  is  shot  from 
the  front  of  the  furnace  to  the  back.  The  heated  gases  in  their 
journey  toward  the  rear  come  in  contact  with  the  lower  set  of 
tubes  and  at  the  rear  they  pass  up  through  the  superheater. 
They  are  then  deflected  back  horizontally  toward  the  front,  pass- 
ing parallel  along  the  water  tubes.  At  the  front  they  return  again 
to  the  rear  along  the  third  set  of  tubes  and  also  along  the  lower 
half  of  the  boiler  drum  above. 

Water  Circulation. — Water  enters  the  upper  set  of  horizontal 
tubes  from  the  front  without  passing  first  into  the  boiler  drum 
above.  At  the  rear  it  is  conveyed  upward  into  the  drum  which 


BOILER  CLASSIFICATION 


119 


120  FUEL  OIL  AND  STEAM  ENGINEERING 

has  a  longitudinal  diaphragm  separating  the  steam  section  above 
from  the  water  section  beneath.  This  water  having  emptied 
upon  the  diaphragm  in  the  upper  compartment  flows  down  along 
the  diaphragm  to  the  front.  At  this  point  it  is  dropped  down  into 
the  next  section  of  tubes  to  be  again  discharged  upward  into  the 
upper  rear  section  to  flow  again  down  along  the  diaphragm  to  the 
front  and  again  to  be  lowered  into  the  lowest  section  of  hori- 
zontal tubes  to  return  into  the  diaphragm  section  above  as  satu- 
rated steam. 

It  is  seen  by  comparing  those  two  types  of  steam  generation 
that  contrary  and  opposite  theories  are  used.  The  first  fires 
the  oil  flame  from  the  back  toward  the  front,  while  the  latter 
applies  the  opposite  process.  The  first  admits  the  water  into 
the  drum  and  then  produces  a  water  circulation  from  the  lower 
sections  upward;  the  latter  takes  the  water  first  through  the  top 
sections  and  winds  up  at  the  lower.  The  first  sets  forth  the 
theory  of  right  angle  impingement  of  heated  gases  against  the 
water  tube  surface  while  the  latter  takes  the  paralleling  flow 
theory.  The  remarkable  thing  about  the  whole  comparison  is 
that  both  have  produced  wonderfully  efficient  steam  generating 
achievements  in  carefully  conducted  fuel  oil  tests  on  the  Pacific 
Coast. 

The  Stirling  Type. — The  Stirling  boiler  consists  of  three  steam 
drums  connected  to  one  mud  drum  by  means  of  bent  tubes.  The 
bending  of  the  tubes  does  away  with  the  necessity  of  using  headers 
and  furthermore  provides  for  expansion  of  the  tubes  due  to  change 
in  temperature.  As  a  result  this  boiler  is  not  only  simple  in  de- 
sign but  very  flexible  and  capable  of  withstanding  a  good  deal  of 
abuse.  The  baffles  are  arranged  in  such  a  manner  that  the  gases 
of  combustion  travel  up  the  front  bank  of  tubes,  down  the  middle 
bank  and  up  the  rear  bank.  Stirling  boilers  are  also  constructed 
with  an  extra  baffle  wall  so  as  to  give  the  gases  a  longer  travel 
before  leaving  the  boiler.  With  this  arrangement  which  is 
known  as  a  four  pass  Stirling  boiler,  the  front  two  or  three  rows 
of  tubes  are  exposed  to  the  furnace,  the  gases  passing  down  the 
remaining  tubes  of  the  front  bank,  up  the  midde  bank,  down  a 
portion  of  the  rear  bank  and  up  the  remaining  rear  tubes  to  the 
stack.  Both  the  standard  three  pass  and  the  four  pass  Stirling 
Boilers  have  proved  very  successful  for  oil  burning. 

Other  boilers  of  the  general  Stirling  type  are  the  Badenhausen, 
the  Rust  boiler  and  the  Erie  City  vertical  boiler. 


BOILER  CLASSIFICATION 


121 


The  Heine  Type. — The  Heine  boiler  is  a  horizontal  water  tube 
boiler  similar  to  the  B.  &  W.  boiler  except  that  instead  of  having 
separate  headers  the  tubes  are  all  expanded  into  a  single  water 
leg  at  the  rear  and  another  at  the  fron-t.  These  water  legs  have 
large  flat  surfaces  which  have  to  be  strengthened  by  stay  bolts. 
Owing  to  the  fact  that  all  of  the  tubes  are  connected  to  the  same 
water  legs,  this  boiler  is  not  as  flexible  as  the  other  two  types 
described  above.  The  Heine  boiler  is  usually  provided  with 


FIG.  71. — The  B.  &  W.  marine  type  of  boiler — front  view. 

Water  tube  boilers  for  marine  service  are  built  as  modifications  of  both  the  B.  &  W.  and 
Heine  type,  the  tubes  being  shorter  and  smaller  in  diameter  than  is  the  case  in  stationary 
boilers.  These  boilers  are  encased  in  steel,  lined  with  light  insulating  material  inside,  in- 
stead of  being  set  in  brick.  They  are  constructed  of  the  highest  grade  of  forged  steel. 
Marine  boilers  frequently  carry  pressures  as  high  as  300  Ib.  per  sq.  in. 

horizontal  baffles  so  that  the  gases  of  combustion  pass  first  to 
the  rear  of  the  boiler  and  then  forward  among  the  tubes  and  then 
back  again.  With  this  arrangement  of  baffling  the  oil  burner 
introduced  through  the  front  wall  is  very  successful.  Other 
boilers  of  the  Heine  type  are  the  Keeler  and  Edgemoor 
boilers. 


122 


FUEL  OIL  AND  STEAM  ENGINEERING 


Marine  Boilers. — For  mercantile  marine  service  the  standard 
boiler  for  many  years  has  been  the  Scotch  marine  boiler  which  is 
a  fire  tube  boiler  consisting  of  a  large  shell  within  which  are 
placed  corrugated  furnaces,  a  combustion  chamber  at  the  rear 
and  tubes  running  forward  from  the  combustion  chamber  to  the 
front  of  the  boiler,  whence  the  gases  pass  through  the  uptakes  to 
the  smokestacks.  Owing  to  the  large  size  of  the  shell,  Scotch 
boilers  are  made  of  excessively  thick  steel  and  consequently  are 


FIG.  72. — The  B.  &  W.  marine  type  of  boiler — rear  view. 

entirely  lacking  in  flexibility.  They  are,  therefore,  liable  to 
give  trouble  due  to  expansion  strains  from  change  in  tempera- 
ture and  are  successful  only  where  the  load  is  absolutely  steady 
as  it  is  on  ordinary  merchant  ships. 

In  the  navy  water  tube  boilers  are  used  exclusively  and  these 
are  coming  into  use  more  or  less  in  the  mercantile  marine  a,s 
well. 

Water  tube  marine  boilers  are  built  as  modifications  of  both 
the  B.  &  W.  and  the  Heine  types,  the  tubes  being  shorter  and 
smaller  in  diameter  than  is  the  case  in  stationary  boilers  and  the 


BOILER  CLASSIFICATION  123 

boilers  being  encased  in  steel,  lined  with  light  insulating  material 
inside,  instead  of  being  set  in  brick. 

For  torpedo  boat  destroyers  and  other  small  high  speed  craft 
boilers  of  the  Thornycroft  type  are  used,  which  consist  of  a  large 
number  of  very  small  diameter  tubes  expanded  into  upper  and 
lower  drums  somewhat  similar  in  general  type  to  the  Stirling 
stationary  boiler.  These  boilers  are  extremely  light  and  are  rapid 
steamers  which  are  necessary  characteristics  of  boilers  for  high 
speed  boats. 


CHAPTER  XVI 


FUEL  OIL  AND  SPECIFICATIONS  FOR  PURCHASE 


ETROLEUM  has  been  known  in  the 
United  States  from  prehistoric 
times.  It  is  certain  that  the  mound 
builders  had  wells  from  which 
petroleum  was  obtained.  These  are 
still  in  existence  along  with  the 
most  modern  of  our  own  times. 

Petroleum  was  used  as  a  medicine 
by  many  tribes  of  Indians.  It  was 
supposed  to  have  many  magical  as 
well  as  medicinal  properties.  Its 
inflammable  nature  seems  also  to 
have  been  known. 

No  use  was  discovered  for  petro- 
leum other  than  as  a  medicine  until 
in  1852,  when  a  chemist,  by  the 


FIG.  73—  The  Saybolt  elec- 
trical equipment  for  flash  and  fire 
tests. 


name  of  Kier,  bethought  himself  of 
distilling  it  and  extracting  from  it 
the  more  volatile  portions.  The 

American  people  took  readily  to  the  use  of  these  oils  as  illumi- 
nating agents  from  the  fact  that  for  some  time  previously  the 
mineral  oils,  extracted  from  lignites  and  anthracites,  according  to 
the  process  of  Sellegries,  the  Swiss  chemist,  were  in  current  use. 
Enormous  Consumption  of  Fuel  Oil  in  the  Industries. — The 
use  of  crude  petroleum  as  a  fuel  for  steam  generation  and  power 
production  has-  now  an  established  position  in  all  parts  of  the 
industrial  world.  Especially  is  this  true  of  the  Pacific  Coast 
and  in  the  southwestern  section  of  the  United  States  where  the 
enormous  yield  of  this  product  in  Oklahoma,  Texas  and  California 
now  constitutes  an  ever-increasing  factor  in  the  total  production 
of  the  world.  Indeed,  California  alone  with  her  yield  of  over  one 
hundred  million  barrels  in  1919  produced  over  25  per  cent,  of  the 
world's  output. 

124 


FUEL  OIL  AND  SPECIFICATIONS  FOR  PURCHASE      125 

At  its  first  incipiency  it  was  thought  that  the  probable  produc- 
tion of  crude  petroleum  would  be  limited  to  but  a  few  years. 
Due  to  this  factor  many  power  plants  on  the  Pacific  Coast  were 
constructed  so  that  an  easy  change  over  to  operation  by  coal 
could  be  made  should  this  time  ever  arrive.  It  is  now  recognized 
by  many  that  the  probable  yield  of  oil  will  last  as  long  as  the  coal 
fields  of  the  world.  Hence  this  uncertainty  is  largely  dispelled  in 
the  industrial  production  of  power. 

Advantages  of  Crude  Petroleum  as  a  Fuel. — Oil  has  many 
distinct  advantages  over  coal.  Due  to  the  simple  mechanisms 
that  are  involved  the  cost  for  handling  fuel  oil  is  far  less  than  for 
coal.  By  the  elimination  of  stokers  an  important  labor  item  is 
found  unnecessary.  Again  for  equal  heat  value  oil  occupies 
much  less  space  than  coal.  Hence  for  ocean-going  vessels  it  is 
especially  applicable.  Combustion  too  is  more  perfect  so  that 
the  quantity  of  excess  air  required  is  reduced  to  a  minimum. 
The  furnace  temperature  may  be  kept  practically  constant  as  the 
furnace  doors  need  not  be  opened  for  cleaning  or  working  the 
fires.  Smoke  may  to  a  large  measure  be  eliminated  with  the  con- 
sequent cleanliness  of  heating  surfaces.  Again,  the  intensity  of 
the  fire  is  subject  to  delicate  regulation  and  sudden  load  fluctua- 
tions are  easily  handled.  Oil  does  not  disintegrate  or  lose  its 
calorific  value  when  stored.  In  the  boiler  room  the  cleanliness 
and  freedom  from  dust  and  ashes  results  in  a  saving  in  wear  and 
tear  in  machinery.  Hence  it  is  clearly  evident  that  the  efficiency 
and  the  steaming  capacity  of  a  boiler,  oil  fired,  is  increased  in  a 
marked  manner. 

The  disadvantages  of  fuel  oil  are  of  comparatively  small 
moment.  For  this  reason  wherever  oil  can  be  obtained  at  a 
reasonable  figure  as  compared  to  the  prevailing  market  price  of 
coal  it  has  attained  a  marked  popularity  in  steam  generation  and 
in  the  industries. 

Let  us  then  look  into  some  of  the  physical  properties  of  this 
new  and  important  source  of  heat  generation. 

Liquid  Fuels  Classified. — Petroleum  is  practically  the  only 
liquid  fuel  sufficiently  abundant  and  cheap  to  be  used  for  the 
generation  of  steam.  There  are  three  kinds  of  petroleum  in  use, 
namely,  those  yielding  on  distillation  paraffin,  asphalt  and  olefine. 
To  the  first  group  belong  the  oils  of  the  Appalachian  Range  and  the 
Middle  West  of  the  United  States.  These  are  a  dark  brown  in 
color  with  a  greenish  tinge.  Upon  their  distillation  such  a  variety 


126  FUEL  OIL  AND  STEAM  ENGINEERING 

of  valuable  light  oils  are  obtained  that  their  use  as  a  fuel  is  pro- 
hibitive because  of  price.  To  the  second  group  belong  the  oils 
found  in  Texas  and  California.  These  vary  in  color  from  reddish 
brown  to  a  jet  black.  Since  they  are  used  extensively  as  a  fuel 
in  the  United  States,  our  discussion  in  this  chapter  shall  largely 
be  concerned  with  this  class  of  oils.  The  third  group  compr  ses 
the  oils  from  Russia,  which  like  the  second  group  are  used  largely 
for  fuel  purposes. 

Physical  and  Chemical  Properties  of  Oil. — Mineral  oils  as 
found  in  nature,  are  a  mixture  in  indefinite  proportions  of  several 
combinations  of  hydrogen  and  carbon  designated  as  hydro- 
carbons. Oxygen  and  sulphur  are  found  in  very  small  amounts. 
Nitrogen  is  found  in  a  smaller  proportion  than  the  latter. 

tOn  account  of  the  complexity  of  their  composition,  mineral 
oils  differ  considerably  both  physically  and  chemically. 

Odor  and  Color. — Oil  is  generally  found  in  a  very  fluid  condi- 
tion in  North  and  South  America,  while  in  Russia  and  East  India 
it  is  found  in  a  very  dense  and  syrupy  condition.  They  all  possess 
a  characteristic  odor  while  their  color  varies  from  amber  or  greenish 
yellow  to  dark  brown.  By  reflection  they  are  all  greenish. 

Effect  of  Heat. — Heat  will  separate  the  different  hydrocarbons 
successively  according  to  their  volatility  and  cause  them  to  dis- 
sociate at  higher  temperatures.  Low  temperatures  will  solidify 
these  products,  the  highest  freezing  at  a  lower  temperature. 

Density  of  Various  Oils. — The  density  varies  from  0.765  to 
0.970  compared  with  water  at  4°C.,  as  found  in  nature  (crude). 
Distillates  will  be  much  lighter. 

DENSITIES  OF  OILS 
Origin  of  crude  Specific  gravity 

Persia 0.777 

East  Indies 0.821 

Kyouk-Phyon  (Burma) 0. 818 

California 0.960 

Pennsylvania 0 . 850 

South  America 0 .  852 

Russia 0.  836 

India 0.955 

Terra-di-Lavors  (Italy) 0.970 

Physical  Properties  of  California  Oils. — We  shall  now  con- 
sider as  a  typical  example  a  sample  of  California  crude  petroleum 
taken  from  an  average  of  forty  samples  drawn  from  the  Kern 
River  oil  field  by  representatives  of  the  U.  S.  Bureau  of  Mines. 


FUEL  OIL  AND  SPECIFICATIONS  FOR  PURCHASE      127 

The  specific  gravity  or  density  of  fuel  oil  is  an  important 
factor  to  be  known  and  is  the  ratio  of  the  weight  of  an  oil  sample 
as  compared  with  the  weight  of  an  equal  volume  of  water.  The 
average  oil  sample  is  found  to  have  a  specific  gravity  of  0.9645, 
which  on  the  Baume  scale  at  60°F.  is  15.16°.  Hence,  the  aver- 
age gallon  of  fuel  oil  weighs  8.03  Ibs. 

The  determination  of  the  gravity  of  fuel  oil  and  the  relation- 
ship of  specific  gravity  with  gravities  expressed  on  the  Baume 
scale  are  of  such  importance  that  a  subsequent  chapter  has  been 
set  aside  for  detailed  discussion  and  analysis. 

The  Calorific  Value  of  Fuel  Oil. — In  steam  boiler  economy 
the  heat  producing  value  of  the  fuel  per  pound  consumed  in  the 


FIG.  74. — Laboratory  equipment  for  fuel  oil  testing. 

In  the  gathering  of  fuel  oil  data  for  boiler  tests  the  three  things  to  be  ascertained  accu- 
rately are  the  specific  gravity,  the  moisture  content,  and  the  calorific  value  of  the  oil  sample. 
The  principal  pieces  of  apparatus  necessary  are  the  Westphal  Balance,  the  chemist's  scales, 
a -Parr  calorimeter,  and  a  still  with  their  accessories  as  shown.  In  the  text  of  this  article 
these  physical  characteristics  of  fuel  oil  are  set  forth.  In  later  discussions  the  laboratory 
procedure  in  order  to  ascertain  each  of  these  points  will  be  discussed  in  separate  chapters. 

furnace  is  of  utmost  importance.  The  average  sample  of  Kern 
River  oil  generates  or  gives  out  10,307  calories  per  gram,  which 
transferred  to  steam  engineering  units  is  found  to  be  18,553 
B.t.u.  per  pound  or  148,980  B.t.u.  per  gallon  of  oil. 

Oil,  like  water,  requires  the  actual  absorption  of  a  large 
quantity  of  heat  in  its  conversion  into  the  gaseous  state.  Indeed 
the  latent  heat  of  evaporation  for  fuel  oil  is  approximately 


128  FUEL  OIL  AND  STEAM  ENGINEERING 

130-150  B.t.u.  per  pound  under  atmospheric  pressure,  as  com- 
pared with  970.4  for  the  latent  heat  of  evaporation  of  water  as 
set  forth  in  previous  discussions.  Hence,  the  actual  heat  given 
out  by  the  average  sample  above  referred  to  is  approximately 
18,700  B.t.u.  per  pound,  but  since  we  must  gasify  the  oil  to  make 
use  of  its  heat  generating  characteristics  in  the  furnace  the  net 
value  of  18,553  is  solely  of  commercial  importance. 

The  determination  of  the  calorific  value  of  fuel  oil  and  the 
many  computations  involved  are  of  such  vast  importance  that 
several  chapters  have  been  set  aside  for  future  discussions  of 
these  various  factors. 

The  Flash  Test  and  the  Burning  Point  of  Oil. — The  flash  test 
of  an  oil  is  the  temperature  at  which  it  gives  off  inflammable 
vapors.  For  the  purpose  of  safety  in  handling,  fuel  oils  should 
not  give  off  inflammable  vapors  below  150°F.  The  flash  point 
of  an  oil  is  determined  by  heating  the  oil  in  a  vessel  adjacent 
to  which  is  a  small  flame.  When  the  oil  has  been  heated  to  a 
point  where  vapor  rises  and  ignites  from  the  flame,  this  tempera- 
ture is  called  the  flash  point.  The  flash  point  of  the  average 
California  oils  is  108°C.  or  226.4°F. 

The  burning  point  of  oil  is  the  temperature  at  which  its  in- 
gredients will  permanently  ignite.  This  is  determined  by 
continuing  the  heating  of  the  oil  after  the  flash  point  has  been 
ascertained  until  the  " flash"  becomes  permanent,  that  is,  until 
the  oil  ignites  and  continues  to  burn  quietly.  For  the  average 
Kern  River  oil  sample  the  burning  point  is  found  by  the  open  cup 
test  to  be  130°C.  or  266°F. 

Viscosity. — Some  oils  are  more  fluid  or  mobile  than  others. 
All  are  familiar  with  the  difference  between  "cold  molasses" 
and  "hot  molasses."  And  so  in  oil  flow  we  have  a  similar 
phenomenon.  This  tendency  for  the  particles  of  oil  to  cohere 
to  one  another  is  known  as  viscosity.  Viscosity  is  determined  by 
measuring  the  time  it  takes  oil  to  flow  through  a  standard  sized 
tube  under  standard  conditions.  On  the  so-called  Engler 
scale  the  average  viscosity  of  Kern  River  oil  at  20°C.  is  found  to 
be  915.6.  The  viscosity  is  very  materially  lessened  as  the 
temperature  is  increased.  Hence  at  once  is  seen  the  advantages 
of  oil  heating  both  for  efficiency  in  transmission  through  long 
pipe  lines,  and  for  feeding  the  oil  to  the  burners.  In  power 
plants  the  oil  is  heated  to  a  temperature  of  160°F.  before  reaching 
the  burners. 


FUEL  OIL  AND  SPECIFICATIONS  FOR  PURCHASE      129 

Moisture. — All  oils  have  a  certain  quantity  of  moisture  present 
either  in  a  free  state  or  in  the  form  of  an  emulsion,  and  its  pres- 
ence is  always  a  hindrance  to  the  full  development  of  the  heat 
producing  qualities  of  the  oil.  Since  this  is  a  matter  of  great 
importance,  the  methods  used  in  the  quantitative  determination 
of  moisture  present  in  fuel  oil  will  be  set  forth  in  a  subsequent 
chapter.  The  average  Kern  River  sample  contains  about  0.5 
per  cent,  moisture.  Hence  the  actual  fuel  oil  ingredient  is 
99.5  per  cent. 

Sulphur,  Gas  and  Other  Ingredients. — All  oils  have  a  certain 
quantity  of  sulphur  present.  This  sulphur  has  a  heat  producing 
quality,  yet  its  deleterious  effect  in  producing  obnoxious  gases 
and  the  corroding  effect  it  has  on  the  boiler  tubes  and  other  metal- 
lic parts  makes  a  certain  excess  of  sulphur  most  undesirable  in 
the  use  of  fuel  oil.  Sulphur  in  burning  forms  sulphur  dioxide, 
SO2,  which,  on  combining  with  water  forms  sulphurous  acid. 
Ordinarily  corrosion  does  not  occur  as  long  as  the  temperature  is 
above  212°F.  Hence  corrosion  of  the  boiler  tubes  is  negligible 
as  long  as  the  boiler  is  kept  in  operation,  but  if  a  boiler  is  used 
for  standby  purposes  and  is  kept  shut  down  a  good  deal  of  the 
time  there  may  be  active  corrosion  of  the  tubes,  and  drum  shells. 
Steel  stacks  are  subject  to  corrosion  from  this  cause,  especially 
the  upper  portions  exposed  to  the  weather,  where  the  cooling 
effect  of  the  metal  causes  condensation  of  the  moisture  in  the  gases. 
The  average  Kern  River  oil  sample  contains 0.83  percent,  sulphur. 
There  is  no  gasoline  ingredient  found  in  this  oil  sample. 
On  the  other  hand,  refined  lamp  oil  appears  to  the  extent  of 
6.6  per  cent,  and  refined  lubricants  to  the  extent  of  39.2  per  cent. 
The  refining  losses  are  5.9  per  cent,  and  distilling  losses,  0.5  per 
cent.  The  commercial  asphaltum  present  is  47.3  per  cent.,  thus 
indicating  why  California  oils  are  known  as  possessing  an  as- 
phaltum base. 

Specifications  for  the  Purchase  of  Oil. — In  the  above  discus- 
sion of  the  physical  properties  of  fuel  oil  it  is  seen  that  the  flash 
point,  burning  point,  viscosity,  heating  value,  moisture  content, 
sulphur  content,  and  other  characteristics  are  fundamentally 
concerned  in  the  commercial  evaluation  of  crude  petroleum. 
"  Below  are  given  "  Notes  on  Specifications  for  the  Purchase  of 
Fuel  Oil"  by  J.  M.  Wadsworth,  published  by  the  U.  S.  Bureau 
of  Mines  in  the  handbook  entitled,  "  Efficiency  in  the  Use  of  Oil 
Fuel."  The  points  set  forth  are  of  fundamental  importance  for 


130  FUEL  OIL  AND  STEAM  ENGINEERING 

the  economic  use  of  fuel  oil  in  all  steam  boiler  practice  and  the 
reader  should  carefully  bear  them  in  mind. 

NOTES  ON  SPECIFICATIONS  FOR  THE   PURCHASE  OF  FUEL  OIL 

1.  In  the  purchase  of  fuel  oil  by  large  users,  all  buying  should 
be  done  under  competitive  bids.     In  determining    the    award 
of  a  contract  consideration  should  be  given  to  the  quality  of  the 
fuel  offered  by  the   bidders,  as  well  as  the  price,  and  should  it 
appear  to  the  best  interest  of  the  purchaser  to  award  a  contract 
at  a  higher  price  than  that  named  in  the  bid  or  bids  received  the 
contract  should  be  so  awarded. 

2.  Each    bidder    should    be  required  to  submit  an  accurate 
statement  regarding  the  fuel  oil  he  proposes  to  furnish.     This 
statement  should  show: 

(a)  The  commercial  name  of  the  oil. 

(6)  The  name  or  designation  of  the  field  from  which  the  oil  is 
obtained. 

(c)  Whether  the  oil  is  crude  oil,  a  refinery  residuum,  a  distil- 
late, or  a  blend. 

(d)  The  name  and  location  of  the  refinery,  if  the  oil  has  been 
refined  at  all. 

3.  The  fuel  oil  should  be  delivered  f.o.b.  cars,  vessels,  tanks, 
or  tank  wagons,  according  to  the  manner  of  shipment  or  delivery 
at  such  places,  at  such  times,  and  in  such  quantities  as  may  be 
required  during  the  fiscal  year  ending . 

3a.     Minimum  and    maximum  weekly  or  monthly  deliveries 
should  be  specified. 

4.  Should  the  contractor,  for  any  reason,  fail  to  comply  with 
the  writtten  order  to  make  delivery,  the  purchaser  is  to  be  at 
liberty  to  buy  oil  in  the  open  market  and  charge  against  the  con- 
tractor any  excessive  price,  above  the  contract  price,  of  the  fuel 
oil  so  purchased. 

5.  It  should  be  understood  that  the  fuel  oil  delivered  during 
the  term  of  the  contract  shall  be  of  the  quality  specified.     The 
frequent  or  continued  failure  of  the  contractor  to  deliver  oil  of 
the  specified  quality  should  be  considered  sufficient  cause  for 
the  cancellation  of  the  contract. 

ESSENTIAL  PROPERTIES  OF  THE  OIL 

6.  Viscosity. — Fuel  oil,  as  regards  viscosity,  may  be  divided 
into  two  general  classes,  namely: 


FUEL  OIL  AND  SPECIFICATIONS  FOR  PURCHASE      131 

Class  1.  Asphaltic  base  crudes,  residuums,  or  other  oils  which 
require  heating  facilities  to  reduce  the  viscosity  in  order  that  the 
oil  may  be  handled  by  the  storage  and  burning  equipment. 

Class  2.  Oils  of  a  sufficiently  low  viscosity  to  make  heating 
equipment  unnecessary. 

In  general,  an  oil  of  Class  1  should  not  have  a  viscosity  above 
2000°  Engler  at  60°F.  Oils  of  a  higher  viscosity  than  this  can 
be  used  at  plants  provided  with  special  equipment.  It  is  im- 
perative that  oils  of  this  class  be  heated  to  a  temperature  at 
which  they  have  a  viscosity  of  12°  Engler  or  lower  before  they 
reach  the  burner,  in  order  to  obtain  proper  atomization.  It  is 
desirable  that  this  viscosity  be  obtained  at  a  temperature  below 
the  flash  point  of  the  oil,  in  order  to  minimize  fire  hazards  and  to 
insure  uniform  feed  to  the  burner. 

For  an  oil  of  Class  2,  12°  Engler  at  60°F.  is  the  approximate 
maximum  viscosity  permissible. 

Method  of  determination :  Viscosity  should  be  determined  with 
a  standard  Engler  instrument  according  to  the  recognized  method 
of  manipulating  this  viscosimeter.  Other  standard  viscosimeters 
may  be  used  in  special  cases  and  their  readings  converted  to 
Engler  degrees  by  means  of  recognized  tables  or  formulas. 

7.  Flash  Point. — In  general  it  is  desirable  that  the  flash  point 
of  Class  1  oils  should  not  be  below  140°F.,  and  that  of  Class  2 
oils  not  below  120°F.     It  should  be  noted  that  for  Class  1  oils, 
specifications  for  flash  point  are  contingent  upon  viscosity  re- 
quirements as  well  as  upon   general  considerations  for  safety 
requirements  and  evaporation  losses. 

Method  of  determination:  Pensky-Martens  closed-cut  tester 
manipulated  according  to  standard  procedure. 

8.  Specific   Gravity. — Specifications   for   specific    gravity   are 
superfluous.     In  case  oil  is  purchased  by  weight  and  measured 
by  volume  an  accurate  determination  of  its  specific  gravity  is 
essential. 

Method  of  determination:  By  specific  gravity  balance,  pycno- 
meter,  or  hydrometer.  If  conversion  of  Baume  readings  to 
specific  gravity  is  necessary  it  is  essential  that  the  Baume  hydro- 
meter be  accurate  and  that  the  proper  modulus  for  this  instru- 
ment be  used.  Specific  gravities  should  be  reported  at  60°F. 
compared  to  water  at  60°F.  If  they  are  determined  at  other 
temperatures  the  temperature  corrections  given  in  Bureau  of 
Standards  Circular  57  should  be  used. 


132  FUEL  OIL  AND  STEAM  ENGINEERING 

9.  Impurities. — The  oil  should  not  contain  more  than  2  per 
cent,  by  volume  of  moisture  and  sediment.     Proper  deductions 
should  be  made  from  all  oil  deliveries  for  the  impurities  contained 
therein  so  that  the  oil  purchased  shall  be  pure  oil. 

Method  of  determination :  A  definite  volume  of  the  oil  sample 
should  be  thoroughly  shaken  or  "cut"  with  an  equal  volume  of 
gasoline  of  a  specific  gravity  not  greater  than  0.74,  and  centri- 
fuged.  An  appropriate  tube  that  goes  with  a  special  machine  is 
commonly  used  for  this  purpose.  Centrifuging  should  be  con- 
tinued until  there  is  a  clear  line  of  demarcation  between  the  water 
and  sediment  and  oil  in  the  bottom  of  the  tube,  and  until  a  con- 
stant reading  of  water  and  sediment  is  obtained.  From  this 
reading  the  percentage  by  volume  of  water  and  sediment  is 
computed.  If  the  oil  under  consideration  has  a  specific  gravity 
greater  than  0.96,  one  volume  of  oil  to  three  volumes  of  gasoline 
should  be  used  rather  than  equal  volumes.  When  there  is  a 
question  that  the  gasoline  used  for  thinning  the  oil  in  making 
this  determination  renders  insoluble  certain  of  its  fuel  constituents, 
then  mixtures  of  gasoline  and  carbon  disulphide,  or  of  gasoline 
and  benzol  may  be  used  for  "cutting,"  providing  the  specific 
gravity  of.  such  mixtures  is  not  greater  than  0.74.  If,  after 
continued  centrifuging,  a  clear  line  of  demarcation  between  the 
impurities  and  the  oil  is  not  obtainable,  the  uppermost  line  should 
be  read.  If  this  procedure  proves  unsatisfactory,  100  cc.  of  the 
sample  may  be  distilled  with  an  excess  of  hydrocarbons  saturated 
with  water  and  having  boiling  points  slightly  above  and  below 
that  of  water.  Distillation  is  continued  until  a  volume  equal 
to  the  volume  of  hydrocarbons  added  has  been  distilled  over 
into  a  graduated  tube.  The  water  in  the  oil  is  thus  distilled 
over  and  readily  collects  at  the  bottom  of  this  tube,  where  the 
percentage  may  be  read  off.  The  percentage  of  sediment  in  the 
oil  may  then  be  determined  on  the  sample  remaining  in  the  dis- 
tilling flask  by  "cutting"  it  with  gasoline  and  centrifuging.  The 
percentage  of  water  obtained  in  the  tube  added  to  the  percentage 
of  sediment  gives  a  total  percentage  to  be  deducted  for  moisture 
and  impurities. 

10.  Sulphur  Content. — Appreciable  sulphur  content  in  a  fuel 
oil  is  objectionable.     However,  a  content  of  4  per  cent,  or  less  is 
not  sufficiently  objectionable  to  cause  the  rejection  of  a  fuel  oil 
for  general  purposes.     (In  general,  experiments  in  burning  fuel 
oils  of  various  sulphur  content  have  shown  that  the  corrosive 


FUEL  OIL  AND  SPECIFICATIONS  FOR  PURCHASE      133 

effects  on  the  boiler  tubes  or  heating  surfaces  are  negligible. 
However,  with  steel  stacks  and  low  stack-gas  temperatures, 
considerable  corrosion  in  the  stack  has  been  noted.  In  handling 
these  oils,  prior  to  burning,  the  corrosive  action  of  the  sulphur 
on  steel  storage  tanks,  piping,  etc.,  is  quite  apparent  and  should 
be  considered.  If  the  oil  is  to  be  used  for  special  metallurgical 
or  other  purposes  where  sulphur  fumes  are  decidedly  objection- 
able, it  is  necessary  to  specify  a  limiting  figure  for  the  sulphur 
content  of  the  oil.) 

Method  of  determination:  Complete  combustion  in  a  bomb 
by  means  of  oxygen  or  sodium  peroxide,  the  sulphur  being  weighed 
as  barium  sulphate. 

11.  Calorific   Value. — A   standard    of    18,500   B.t.u.    to   the 
pound  of  pure  fuel  oil  is  a  good  figure  to  be  taken  as  the  basis,  if 
the  fuel  oil  is  to  be  purchased  on  calorific  determinations.     A 
bonus  may  be  paid  for  calorific  value  in  excess  of  this  figure  and 
deductions  made  if  the  heating  value  of  the  fuel  is  below  18,500 
B.t.u.  per  pound. 

Method  of  determination :  Any  bomb  calorimeter  of  recognized 
accuracy. 

12.  Methods  of  Sampling. — The  accuracy  of  these  different 
tests  depends  upon  the  care  with  which  an  average  representative 
sample  of  the  fuel  oil  delivery  has  been  taken,  and  the  importance 
of  obtaining  such  a  sample  can  not  be  overestimated.     Top, 
middle,  and  bottom  samples  should  be  taken  with  a  standard 
"car  thief"  and  these  samples  should  be  combined  and  thoroughly 
mixed   to  form   one   sample  for   car   deliveries.     Where   oil  is 
received  in  tanks  or  reservoirs  the  swing  pipe  should  first  be 
locked  at  a  position  well  above  the  level  of  the  water  and  sedi- 
ment usually  found  in  the  bottom  of  such  tanks.     Tanks  should 
be  sampled  every  foot  for  the  first  5  feet  above  the  bottom  of  the 
swing  pipe,  and  at  5-ft.  intervals  from  there  to  the  surface  of  the 
oil.     This  sampling  should  be  done  with  a  standard  tank  thief, 
the  samples  "cut"  individually,  and  deductions  for  impurities 
made    on    the    separate   volumes  which    these    samples   repre- 
sent.    If  the  tank  is  a  large  one,  it  should  be  sampled  through 
at  least  two  hatches.     In  receiving  large  deliveries  of  the  more 
viscous  oils  it  is  necessary  to  take  many  samples  in  order  to 
insure  fair  and  average  impurity   (M.  and  B.  S.)   deductions. 
This  is  because  water  and  sediment  do  not  readily  settle  out  of 
such  oils. 


134  FUEL  OIL  AND  STEAM  ENGINEERING 

13.  General  Specifications  can  not  be  Drawn  to  Advantage 
for  Fuel  Oils. — Individual  conditions  and  requirements  at  the 
points  of  consumption  influence  to  a  large  degree  the  specifications 
for  viscosity,  flash  point,  and  sulphur  content.  Definite  speci- 
fications can  be  drawn  for  a  fuel  oil  which  will  meet  practically 
all  requirements,  but  it  can  readily  be  seen  that  such  specifications 
will  exclude  much  of  the  fuel  oil  now  available,  and  for  most 
purposes  the  requirements  need  not  be  severe.  Hence,  it  is 
advised  that  in  purchasing  fuel  oil  the  individual  requirements  be 
studied  and  that  as  lenient  specifications  as  possible  be  written 
which  will  insure  an  oil  that  will  be  satisfactory  for  the  conditions 
for  which  it  is  intended. 


CHAPTER  XVII 
FUEL  OIL  PRICES  AND  OIL  PRODUCTION 

By  October  1920,  as  this  Second  Edition  of  "Fuel  Oil  and  Steam 
Engineering"  is  about  to  go  to  press,  the  authors  have  come  to 
the  realization  of  the  fact  that  the  price  of  California  fuel  oil 
has  more  than  doubled  since  the  first  edition  of  this  book  appeared 
just  two  years  ago.  Since,  then,  the  constantly  depleting  storage 
of  oil  by  the  large  production  companies  is  making  marked  in- 
roads into  the  possible  supply  of  fuel  oil  in  the  near  future,  a 
discussion  of  this  is  of  vital  interest  to  the  subject  matter  of  this 


FIG.  75. — Water  softening  plant  at  the  Sierra  and  San  Francisco  Power  Com- 
pany's 27,000  kw.  oil  burning  station.  The  use  of  pure  water  free  from  scale 
forming  matter  is  the  first  requisite  toward  keeping  boilers  clean. 

book  in  that  economy  production  in  the  power  plant  depends 
directly  upon  the  prices  of  this  commodity  prevailing  in  the  open 
market  and  the  ability  of  the  operator  to  obtain  fuel  supply. 

For  the  following  able  discussion  of  this  matter  we  are  in- 
debted to  J.  E.  Woodbridge,  formerly  chief  engineer  of  the  Sierra 
and  San  Francisco  Power  Company. 

135 


136  FUEL  OIL  AND  STEAM  ENGINEERING 

The  exercise  of  prophecy  in  the  field  of  prices  is  beset  with  pitfalls, 
as  has  been  shown  by  the  totally  unexpected  price  revolution  of  the  last 
five  years.  However,  as  all  business  must  be  planned  in  part  on  future 
price  probabilities,  we  are  obliged  to  make  the  best  attempt  we  can  at 
an  estimate  of  their  trend. 

In  the  matter  of  fuel  in  the  state  of  California,  the  most  pertinent 
data  for  prediction  as  to  future  prices  are  the  trend  of  the  last  few  years, 
including  the  recent  history  of  production  and  consumption,  with  other 
relevant  information,  such  as  the  influence  of  the  war,  probable  future 
additional  sources  and  markets. 

PRICE  FLUCTUATION 

Except  for  the  continuity  of  the  thought,  we  need  hardly  inform 
readers  of  this  book  that  the  price  of  delivered  fuel  oil  in  California  has 
advanced  during  the  last  five  years  from  approximately  60^  to  approxi- 
mately $1.85  per  barrel,  the  two  approximations  covering  slight  varia- 
tions with  locality.  The  figure  which  directly  influences  the  production 
of  oil  in  California,  and  constitutes  the  basic  element  of  all  prices  to 
consumers  is  the  market  price  offered  by  the  large  distributing  organiza- 
tions to  the  producers  in  the  oil  fields.  The  price  offered  by  the 
Standard  Oil  Company  of  California  for  fuel  oil,  that  is  oil  having  a 
specific  gravity  between  14°  and  17.9°  on  the  Baume  scale,  has  gone 
through  the  following  changes  during  the  last  six  years. 

On  October  3,  1914,  this  price  dropped  from  40^.  per  barrel  to  37K^- 

June  7,  1915.  . $0.32^ 

Oct.  26,  1915 0.37>£ 

Nov.  20,  1915 0.40 

Dec.  28,  1915 , 0.43 

Feb.  2,  1916 0.48 

Feb.  16,  1916 0 . 53 

April  1,  1916 0.58 

July  7,  1916 0.63 

Sept.  20,  1916 0.68 

Nov.  21,  1916 0.73 

May  11,  1917 0.78 

June  7,  1917 0.88 

June  28,  1917 0.98 

May  1,  1918 1.23 

Mar.  17,  1920 1.48 

The  price  doldrums  of  1915  were  due  to  the  large  number  of  gushers 
brought  in  during  the  years  1913  and  1914,  which  resulted  in  a  produc- 
tion so  much  in  excess  of  consumption  that  a  stock  of  approximately 
60,000,000  barrels  of  oil  (nearly  a  year's  consumption)  was  accumulated 
early  in  1915.  The  price  advances  during  the  subsequent  three  years 
were  largely  due  to  war  demands  and  the  depreciation  of  our  currency, 


FUEL  OIL  PRICES  AND  OIL  PRODUCTION  137 

which  made  oil  field  development  difficult  and  expensive.  In  particular, 
the  large  jump  of  May  1,  1918,  was  made  at  the  request  of  the  National 
Fuel  Administrator.  The  price  advance  and  other  factors  so  stimulated 
production  and  controlled  consumption  that  stock  increased  during  a 
portion  of  1918  and  1919  by  3,000,000  barrels.  Many  who  have  not 
looked  further  into  the  fuel-oil  situation  have  reasoned,  from  the  above, 
that  we  may  rest  easy  as  to  the  price  of  this  raw  material  in  the  im- 
mediate future.  However,  it  does  not  behoove  power  companies  to 
"sleep  at  the  switch."  Let  us,  therefore,  look  a  little  deeper  into  the 
prospect. 

DECREASING  SUPPLY 

On  the  occasion  of  the  last  price  change  of  March,  1920,  the  California 
Railroad  Commission  criticized  the  Standard  Oil  Company  of  California, 
in  response  to  which  President  Kingsbury  of  that  company  answered  in 
part  as  follows: 

"The  Pacific  Coast  supply  of  fuel  oil  and  of  petroleum  products  is 
rapidly  approaching  exhaustion.  Since  May  1,  1915,  crude  oil  stocks 
in  California  have  decreased  from  over  60,000,000  barrels  to  28,738,921 
barrels  oh  March  1,  1920. 

"The  available  supply  of  crude  oil  in  stock  is  today  less  than 
13,000,000  barrels. 

"The  balance  of  the  stocks  are  taken  up  in  the  factor  of  safety  of 
10,000,000  barrrels,  which  the  Petroleum  Committee  of  the  State 
Council  of  Defense  found  essential  to  the  safety  of  Pacific  Coast  in- 
dustries, and  in  the  oil  in  pipe  lines  and  tank  bottoms  which  the  same 
committee  estimated  at  6,000,000  barrels  not  available  for  use. 

"At  the  present  rate  of  consumption  and  of  production  the  available 
stocks  will  be  exhausted  in  about  twelve  months,  at  which  time 
consumers  of  California  fuel  oil  will  be  cut  off  from  between  25,000  to 
30,000  barrels  per  day." 

"In  1918  the  average  daily  consumption  was  279,576  barrels;  in  the 
last  half  of  1919  it  was  292,278  barrels;  in  January,  1920,  301,000  barrels 
and  in  February,  1920,  304,120  barrels. 

"Superimposed  on  these  figures  is  the  fact  that  7,000  barrels  of  fuel  oil 
a  day  which  formerly  went  to  Arizona  from  California  are  now  supplied 
from  Texas  and  Mexico.  The  existing  shortage,  therefore,  has  devel- 
oped in  face  of  the  fact  that  2,500,000  barrels  of  fuel  oil  a  year  have  been 
restored  to  the  California  supply. 

"Added  to  these  considerations  are  the  demands  of  the  navy  and  the 
United  States  Shipping  Board. 

"The  former  estimates  its  1920  requirements  on  the  Pacific  Coast  at 
2,950,800  barrels,  against  1,532,650  barrels  in  1919.  The  Shipping 
Board  has  invited  bids  for  1920  for  4,000,000  barrels. 

"The  United  States  Shipping  Board  is  establishing  oil  fueling  stations 


138 


FUEL  OIL  AND  STEAM  ENGINEERING 


throughout  the  world,  and  will  supply  these  points  from  the  cheapest 
markets.  Thus  California  will  be  drawn  upon  or  spared  in  the  relation 
that  California  prices  bear  to  prices  elsewhere.  Even  at  the  new  price 
this  oil  market  is  lower  than  many  other  points  with  which  this  market 
is  in  competition. 

"The  inevitable  result  will  be  that  the  Pacific  Coast  will  be  further 
drained  of  its  supply  by  buyers  who  seek  the  cheapest  market. 

"  Shipping  Board  vessels  already  have  sought  cargoes  of  fuel  oil  which 
formerly  were  obtained  in  Mexico,  so  that  the  Mexican  cargoes  could 
be  released  for  the  Atlantic  coast. 

"  There  is  further  the  fact  that  improved  refining  processes  will  in- 
crease the  volume  of  refined  products  extracted  from  crude  oil  and  thus 
reduce  the  resulting  residuum  for  fuel  oil. 

"The  company  is  now  installing  at  a  cost  of  $10,000,000  new  processes 
by  which  it  is  estimated  that  more  refined  products,  incuding  gasoline, 
will  be  recovered  from  crude  oil  in  such  quantities  that  the  company's 
production  of  fuel  oil  within  a  year  will  be  necessarily  lessened  about 
30  per  cent,  or  20,000  barrels  a  day." 

Further  light  on  the  probable  price  trend  is  obtainable  from 
the  following  table  of  production  and  consumption  of  crude 
oil  of  all  gravities  in  and  from  the  California  fields  during  the 
last  seven  years. 


Year 

No.  produc- 
ing wells, 
Dec.  31 

Production 

Average 
daily 
production 
per  well 

Consump- 
tion* 

Total 
stocks 
Dec.  31 

1912 

5,626 

90,074,000 

44 

86,500,000 

46,698,000 

1913 

5,870 

97,867,000 

46 

96,695,000 

47,870,000 

1914 

6,106 

103,624,000 

46 

92,968,000 

58,526,000 

1915 

6,532 

89,567,000 

38 

90,946,000 

•57,147,000 

1916 

7,333 

91,822,000 

34 

104,933,000 

44,036,000 

1917 

8,053 

97,268,000 

33 

108,854,000 

32,450,000 

1918 

8,606 

101,638,000 

32 

102,045,000 

32,043,000 

1919 

9,127 

101,222,000 

30 

102,785,000 

30,480,000 

*  Consumption  is  here  taken  as  production  plus  withdrawals  from  storage 
or  less  additions  to  storage,  as  the  case  may  be. 

Examining  the  column  headed  "  production, "  the  gusher 
peak  of  1914,  amounting  to  over  103,000,000  barrels  from  approxi- 
mately 6000  wells  will  be  noted.  A  significant  fact  is  that  less 
oil  was  produced  in  1919,  in  spite  of  a  price  three  times  as  high  as 
that  of  1914.  In  the  meantime  the  number  of  wells  has  in- 


FUEL  OIL  PRICES  AND  OIL  PRODUCTION  139 

creased  50  per  cent.  The  average  production  per  well,  of  today, 
has  gradually  fallen  from  that  of  the  gusher  period  to  30  barrels 
in  1919.  This  means  that  a  large  number  of  wells  are  approach- 
ing the  marginal  production  below  which  it  will  not  be  profitable 
to  pump  them,  unless  the  price  advances.  The  average  rate 
at  which  the  production  of  California  wells  declines  is  fairly 
well  established  for  the  first  few  years  of  their  life.  The  following 
table  gives  the  average  production  of  California  oil  wells  by 
years  of  life  in  percentages  of  production  of  the  first  year. 

1st  year.  . 100 

2nd  year 68 

3rd  year 51 

4th  year 41 

5th  year 33 

Obviously,  as  the  fields  grow  older,  and  the  gushers  become 
only  a  recollection,  the  wells  become  more  crowded,  the  gas 
pressure  goes  down,  and  initial  production  of  the  new  wells 
drilled  becomes  less  and  less  year  by  year,  a  continuously 
expanding  drilling  program  must  be  carried  out  to  keep  up  a  con- 
stant supply.  If,  on  top  of  that,  the  demand  increases,  condi- 
tions are  still  more  strained  for  the  old  law  of  supply  and  demand. 

The  future  price  trend  would,  of  course,  be  checked  in  its 
upward  career,  by  the  development  of  new  oil  fields  within 
reasonable  shipping  distances.  While  no  one  can  predict  posi- 
tively that  new  oil  fields  will  not  be  developed,  it  is  highly  im- 
probable that  the  production  of  any  such  fields,  on  the  Pacific 
Coast,  will  be  sufficient  materially  to  lower  the  California  price. 
Freight  rates  from  the  mid-continent  fields  prohibit  importation 
from  that  source,  even  if  mid-continent  prices  were  lower  than 
our  own.  Mexican  oil  is  still  further  out  of  reach  on  account 
of  freight  rates  by  any  route.  The  only  other  source  in  sight  is 
Colombia  and  Venezuela,  but  the  probable  tanker  rate  of  a 
dollar  or  more  for  the  3000-mi.  haul  will  prevent  this  source 
from  ever  giving  us  cheap  oil,  even  if  the  price  at  the  source  is  not 
held  high,  as  it  undoubtedly  will  be  by  East-coast  demands  and 
by  the  large  volume  of  shipping  through  the  Canal  which  will  in 
future  utilize  oil  fuel  for  propulsion. 

A  NECESSARY  DEVELOPMENT 

The  point  we  wish  to  make  from  the  above  data  is  that  power 
development,  as  in  the  ordinary  steam  station,  at  an  average 


140  FUEL  OIL  AND  STEAM  ENGINEERING 

efficiency  of  185  to  200  kw-hr.  per  barrel,  will  cost  for  fuel  alone 
at  least  one  cent  per  kw-hr.  with  fuel  prices  of  $1.85  upwards. 
This  figure,  added  to  other  steam  operating  costs  and  all  fixed 
charges,  makes  the  total  cost  of  power  so  developed  much  higher 
than  that  of  hydro-electric  power,  even  at  present  high  costs  of 
money  and  construction.  This  being  the  case  for  steam-turbine 
plants  of  reasonably  fair  to  good  efficiencies,  it  is  much  more  true 
of  the  steam  locomotive  with  its  wasteful  boiler  and  non-con- 
densing reciprocating  engine. 

In  other  words,  the  cost  of  the  fuel  oil  alone  used  in  the  steam 
locomotives  in  California  and  neighboring  states,  based  on  its 
value  at  the  market  (amounting  to  approximately  $50,000,000 
per  annum  which  will  increase  year  by  year  until  this  fuel  can 
with  difficulty  be  obtained  at  all)  will  in  time  compel  the  steam 
railroads  to  seek  other  methods  of  operation,  chief  and  most 
promising  of  which  is  electrical.  Disregarding  all  other  reasons 
and  arguments  for  electrification,  the  cost  of  fuel  is  going  to  force 
it. 

Coal  is,  of  course,  a  possible  substitute.  On  a  thermal-unit- 
cost  basis,  Utah  coal  is  now  on  a  par  with  oil  on  the  Sierra  grades. 
Much  as  the  dyed-in-the-wool  steam  railroad  man  mistrusts 
electrification,  we  believe  he  would  have  a  greater  dislike  for  the 
use  of  coal  where  he  has  been  accustomed  to  oil,  on  account  of  its 
inconvenience  in  firing  large  furnaces.  Pulverization  offers  a 
possible  means  of  overcoming  these  difficulties  but  involves  many 
complications  over  the  use  of  oil. 

In  view  of  the  inability  of  the  power  companies  to  meet  their 
present  commercial  demands,  and  the  apparently  insuperable 
financial  program  involved  in  meeting  future  demands,  a  large 
railroad  load  cannot  be  anticipated  with  any  great  degree  of 
satisfaction.  The  solution,  however,  is  obvious — namely,  a 
railroad  power  rate  which  will  finance  the  necessary  development. 

The  hope  for  the  situation  seems,  then,  to  be  in  the  electrifica- 
tion of  the  steam  railroads,  and  thus  the  conservation  of  fuel  oil 
which  will  retrieve  the  depleting  of  the  stocks  now  on  hand 
will  be  brought  about.  The  entire  matter  is  of  the  utmost  con- 
cern and  its  varying  characteristics  from  month  to  month  will  be 
followed  by  the  public  and  particularly  by  the  steam  power 
plant  engineer  with  the  keenest  interest. 


CHAPTER  XVIII 
THE  SAFE  OPERATION  OF  STEAM  BOILERS 

Many  fatal  accidents  both  to  life  and  property  have  happened 
due  to  foolhardy  methods  in  design  and  operation  of  the  steam 
boiler.  This  early  became  so  apparent  that  rigid  governmental 
inspection  of  boiler  operation  was  insisted  upon.  To  aid  in 
systematic  inspection  the  Department  of  Commerce  and  Labor 
at  Washington  has  issued  general  rules  and  regulations  for  such 
supervision  under  Form  801  entitled  Steamboat  Inspection 
Service.  Many  insurance  companies  have,  too,  put  into  force 
rigid  rules  of  inspection  to  safeguard  their  interests  in  assuming 
risks.  The  most  complete  publication  on  the  subject,  however, 
is  to  be  found  in  the  recently  published  report  of  the  Boiler 
Code  Committee  of  the  American  Society  of  Mechanical  Engi- 
neers, entitled:  " Rules  for  the  Construction  of  Stationary  Boilers 
and  for  Allowable  Working  Pressure."  These  rules  have  been 
adopted  by  law  in  a  number  of  States,  including  California  where 
they  have  been  incorporated  in  the  Safety  Orders  of  the  State 
Accident  Commission. 

In  the  discussion  taken  up  in  this  chapter  only  fundamentals 
will  be  considered.  The  thorough  mastering  of  these  funda- 
mentals will,  however,  enable  the  reader  to  understandingly  read 
the  deeper  discussions  alluded  to  above. 

The  Inspection  Tests  Involved. — The  testing  of  the  water  and 
steam  gages,  the  checking  of  fittings  and  appliances,  and  the  try- 
ing out  of  the  safety  valves  and  other  accessories  constitute,  of 
course,  important  details  of  boiler  inspection.  The  most  im- 
portant feature,  however,  is  to  ascertain  by  computation  the 
maximum  allowable  working  pressure  that  may  be  safely  put 
upon  the  boiler.  After  this  maximum  allowable  pressure  is 
ascertained  the  boiler  is  subjected  to  a  hydrostatic  pressure  test 
by  filling  the  boiler  completely  with  water  and  then  pumping 
enough  additional  water  into  it  to  raise  the  pressure  to  the  de- 
sired point.  This  apparatus  is  held  under  proper  control  and 
the  total  pressure  put  upon  the  boiler  is  one  and  one-half  times 
the  maximum  allowable  working  pressure. 

141 


142 


FUEL  OIL  AND  STEAM  ENGINEERING 


Thus  if  the  maximum  allowable  working  pressure  on  a  boiler 
is  160  Ibs.  per  sq.  in.  above  the  atmosphere,  the  test  pressure  to 
be  applied  should  be  240  Ib.  per  sq.  in. 

Many  carefully  compiled  instructions  have  from  time  to  time 
been  issued  by  various  boiler  makers,  inspectors,  and  others 
interested  in  economic  and  safe  operation.  The  instructions 
compiled  by  J.  B.  Warner  chief  inspector  of  the  San  Francisco 


FIG.  76. — An  inspector's  testing  and  proving  outfit. 

Here  is  a  typical  outfit  for  boiler  and  power  plant  inspectors.  It  consists  of  a  standard 
test  gage,  a  screw  test  pump,  a  gage  hand  puller,  a  hand  set  and  other  useful  conveniences. 

department  of  the  Hartford  Steam  Boiler  Inspection  and  In- 
surance Company  are  especially  good,  and  largely  the  ideas  ap- 
pearing in  the  following  lines  come  from  this  source: 

Preliminary  Precautions. — Whenever  going  on  duty  in  the 
boiler  room,  find  out,  first  of  all,  where  the  water  level  is  in  the 
boilers.  Never  lower  nor  replenish  the  fires  until  this  is  done. 


THE  SAFE  OPERATION  OF  STEAM  BOILERS  143 

Make  sure  that  the  gage  glass  and  gage  cocks,  and  all  the  con- 
nections thereto,  are  free  and  in  good  working  order.  Do  not 
rely  upon  the  glass  altogether,  but  use  the  gage  cocks  also,  and 
try  them  all,  several  times  a  day. 

Before  starting  up  the  fires,  open  each  door  about  the  setting 
and  look  carefully  for  leaks.  If  leaks  are  discovered,  either  then 
or  at  any  other  time,  they  should  be  located  and  repaired;  but 
cool  the  boiler  off  first.  If  leaking  occurs  at  the  fore  and  aft 
joints,  the  inspecting  company  should  be  notified  at  once.  This 
is  important,  whether  the  attendant  considers  the  leakage  serious 
or  not ;  and  it  is  especially  important  when  the  boiler  has  a  single 
bottom  sheet,  or  is  of  the  two-sheet  type. 


FIG.  77. — A  portable  boiler  test  pump. 

After  the  maximum  allowable  working  steam  pressure  for  the  boiler  has  been  computed, 
the  boiler  is  then  submitted  to  a  hydrostatic  test  of  one  and  one-half  times  this  allowable 
pressure.  The  above  apparatus  is  especially  adapted  for  those  having  frequent  occasion 
to  make  hydrostatic  tests  of  boilers. 

When  a  boiler  has  been  emptied  of  water,  do  not  fill  it  again 
until  it  has  become  cold. 

In  preparing  to  get  up  steam  after  the  boiler  has  been  out  of 
service,  be  sure  that  the  manhole  and  hand-hole  joints  are  tight. 
Do  not  use  gaskets  that  are  thin  and  hard. 

Vent  the  boiler  in  some  way,  first,  to  permit  the  escape  of  air. 
Then  fill  the  boiler  to  the  proper  level,  open  the  dampers,  and 
start  the  fires.  Start  them  early  so  as  to  have  the  pressure  up 
the  required  hour,  without  forcing. 

Ventilate  the  setting  thoroughly  before  lighting  the  fire. 
Never  turn  on  the  fuel  supply  when  starting  up  without  first 


144  FUEL  OIL  AND  STEAM  ENGINEERING 

placing  in  the  furnace  a  lighted  torch  or  a  piece  of  burning  waste 
to  ignite  the  fuel  instantly. 

Connecting  up  Boiler  Units. — In  firing  up  a  boiler  that  is  to 
be  connected  with  others  that  are  already  in  service,  keep  its 
stop-valve  closed  until  the  pressure  within  the  boiler  has  become 
exactly  equal  to  that  in  the  steam  main.  Then  open  the  stop 
valve  a  bare  crack,  and  slowly  increase  the  opening  until  the  valve 
is  wide  open.  The  complete  operation  should  occupy  two  min- 
utes or  more.  Close,  the  valve  at  once  if  there  is  the  slightest 
evidence  of  any  unusual  jar  or  disturbance  about  the  boiler. 
See  that  the  steam  main  to  which  the  boiler  is  to  be  connected 
is  thoroughly  drained  before  the  valve  is  opened. 

Low  Water  Encountered. — In  case  of  low  water,  immediately 
shut  off  the  oil  supply  at  the  burners.  Do  not  turn  on  the 
feed  under  any  circumstances,  and  do  not  open  the  safety- 
valve  nor  tamper  with  it  in  any  way.  Let  the  steam  outlets 
remain  as  they  are.  Get  your  boiler  cool  before  you  do  any- 
thing else. 

Avoid  Making  Repairs  Under  Pressure. — No  repairs  of  any 
kind  should  be  made,  either  to  boilers  or  to  piping,  while  the 
part  upon  which  the  work  is  to  be  done  is  under  pressure.  This 
applies  to  calking,  to  tightening  up  bolts  under  pressure,  and  to 
repairs  of  any  kind  whatsoever. 

The  safety-valve  must  not  be  set  at  a  pressure  higher  than 
that  permitted  by  the  insurance  company's  policy.  Try  all 
safety-valves  cautiously,  every  day.  If  the  actual  blowing 
pressure,  as  shown  by  the  gage,  exceeds  the  pressure  at  which  the 
valve  is  supposed  to  blow,  inform  the  office  immediately,  so  that 
prompt  notice  may  be  sent  to  the  company.  The  safety-valve 
pipe  should  never  have  a  stop-valve  upon  it. 

Removal  of  Sediment. — To  remove  sediment  from  the  bottom 
of  the  boiler,  open  the  blowoff  valve  in  the  morning,  or  before  the 
circulation  has  started  up.  The  valve  should  be  opened  wide  for 
a  few  moments,  but  it  should  be  opened  and  closed  slowly,  so  as 
to  avoid  shocks  from  water-hammer  action.  When  surface 
blowoffs  are  used,  they  should  be  opened  frequently  for  a 
few  minutes  at  a  time. 

In  case  of  foaming,  check  the  draft  and  shut  off  the  burners. 
Shut  the  stop-valve  long  enough  to  find  the  true  level  of  the 
water.  If  this  is  sufficiently  high,  blow  down  some  of  the  water 
in  the  boiler,  and  feed  in  some  fresh.  Repeat  this  several  times 


THE  SAFE  OPERATION  OF  STEAM  BOILERS  145 

if  necessary.     If  the  foaming  does  not  stop,   cool  the  boiler  off, 
empty  it,  and  find  out  the  cause  of  the  trouble. 

Keep  Out  Cylinder  Oil. — Cylinder  oil  must  be  kept  out  of  the 
boilers,  because  it  is  likely  to  cause  overheating  of  the  plates. 
Oily  deposits  may  be  removed,  in  large  measure,  by  scraping  and 
scrubbing,  although  more  efficient  methods  of  treatment  may  be 
required  in  bad  cases.  If  kerosene  is  used  in  a  boiler,  keep  all 
open  lights  away  from  the  manholes  and  handholes,  both  when 
applying  the  kerosene,  and  upon  opening  the  boiler  up  afterwards ; 
and  ventilate  the  inside  of  the  boiler  thoroughly,  after  oil  has 
been  used  in  it. 

Cooling  and  Cleaning  the  Boiler. — In  cooling  a  boiler  before 
emptying  it,  first  let  the  fire  die  out,  and  then  close  all  doors  and 
leave  the  damper  open  until  the  pressure  falls  to  the  point  at 
which  it  is  desired  to  blow.  Clean  the  furnace  and  let  the  brick- 
work cool  for  at  least  two  hours  before  opening  the  blowoff 
valve.  If  it  is  desired  to  cool  the  boiler  further,  after  it  has  been 
emptied  open  the  manhole  and  leave  everything  else  as  in  full 
actual  service — the  fire  doors,  front  connection  doors,  and  clean- 
ing doors  being  closed,  and  the  damper  and  ash-pit  doors  open. 

First  cool  the  boiler  as  explained  in  the  last  paragraph.  Never 
blow  out  under  a  pressure  exceeding  ten  or  (at  most)  fifteen 
pounds  by  the  gage.  If  time  will  permit,  the  boiler  should  be 
left  full  of  water  for  two  or  three  days  after  shutting  down.  This 
prevents  the  scale  baking  to  the  tubes  so  it  remains  softer  and  is 
more  easily  removed. 

The  engineer  must  find  out  for  himself  how  often  his  boilers 
need  to  be  opened  and  cleaned.  In  many  plants  it  is  necessary 
to  clean  every  week,  while  in  some  favored  few  it  is  sufficient  to 
clean  every  three  months.  -When  using  kerosene  or  large  amounts 
of  scale  solvent,  or  when  (as  in  the  spring-time)  the  water  be- 
comes unusually  soft,  the  boilers  must  be  opened  oftener  than  usual. 
In  washing  out  a  boiler,  wash  the  tubes  from  above,  as  well  as 
from  below. 

Never  touch  any  valve  whatsoever,  in  any  part  of  the  room, 
while  a  man  is  inside  of  a  boiler,  nor  even  after  he  has  come  out 
again,  until  he  has  reported  that  his  work  is  finished  and  that  he 
will  not  enter  the  boiler  again.  It  is  well  to  lock  the  stop- valve 
and  blowoff  valve  upon  every  boiler  in  which  a  man  is  working, 
while  other  boilers  are  under  steam.  Padlocks  and  chains 
may  be  used  for  this  purpose. 
10 


146  FUEL  OIL  AND  STEAM  ENGINEERING 

In  water-tube  boilers  the  covers  opposite  the  three  rows  of 
tubes  nearest  the  fire  should  be  taken  off  once  a  month,  and  the 
tubes  thoroughly  scraped  and  washed  out ;  and  all  the  tubes  should 
be  thoroughly  scraped  and  washed  out  at  least  once  in  four 
months.  This  is  for  water  of  average  quality.  If  the  water  is 
bad,  clean  the  tubes  oftener. 

When  mechanical  hammers  or  cleaners  are  employed  for 
removing  scale  from  tubes,  the  pressure  used  to  operate  them 
should  be  as  low  as  will  suffice  to  do  the  work.  Do  not  allow  the 
cleaner  to  operate  for  more  than  a  few  seconds  upon  any  one 
spot,  and  see  that  it  goes  entirely  through  the  tube.  Avoid  high 
temperatures  in  the  steam  or  water  used  to  operate  the  cleaner. 

Putting  Boiler  Out  of  Service. — In  putting  a  boiler  out  of 
service,  it  should  be  cooled,  emptied,  and  thoroughly  cleaned, 
both  inside  and  outside.  The  setting  should  likewise  be  cleaned 
in  all  its  parts.  Leave  the  handhole  covers  and  manhole  plates 
off.  After  washing  the  interior  of  the  boiler,  let  it  drain  well. 
Then  see  that  no  moisture  can  collect  anywhere  about  the  boiler, 
nor  drip  upon  it  either  internally  or  externally.  Empty  the 
siphon  below  the  steam  gage  if  the  boiler  room  is  likely  to  be  cold, 
or  take  the  gage  off  and  store  it  safely  away. 

Do  not  allow  moisture  to  come  in  contact  with  the  outside  of 
the  boiler  at  any  time,  either  from  leaky  joints  or  otherwise. 
Keep  the  mud  drums  and  nipples,  and  the  rear  ends  of  horizontal 
and  inclined  tubes  in  water-tube  boilers,  free  from  sooty  matter. 
If  internal  corrosion  is  discovered,  notify  your  employers  at 
once. 

Examine  your  boilers  carefully  in  all  their  parts,  whenever  they 
are  laid  off,  and  keep  them  as  clean  as  possible,  both  inside  and 
outside.  See  that  all  necessary  repairs  are  made  promptly  and 
thoroughly.  Keep  the  water  glass  and  pressure  gage  clean  and 
well  lighted.  If  any  contingency  arises  that  you  do  not  under- 
stand, report  the  matter  to  your  employers  at  once;  and  if  you 
think  it  possible  that  serious  trouble  may  be  impending  at  any 
time,  shut  down  the  boiler  immediately. 

Inform  yourself  respecting  any  local  laws  or  ordinances  relating 
to  the  duties  of  engineers  and  firemen,  or  to  the  plant  in  which 
you  work.  If  there  be  any  such,  attend  to  them  faithfully. 


CHAPTER  XIX 
HOW  TO  COMPUTE  STRENGTH  OF  BOILER  SHELLS 

In  order  to  ascertain  by  computation  the  maximum  allowable 
pressure  we  must  first  compute  the  bursting  strength  of  the 
solid  boiler  shell,  then  find  the  weakest  part  of  this  shell,  which, 
of  course,  will  give  us  the  point  where  the  shell  would  really  give 
way.  We  next  compute  the  steam  gage  pressure  that  would 
cause  the  boiler  to  rupture  at  its  weakest  point.  This  is  known 
as  the  bursting  pressure.  It  is  important  to  note  here  the  differ- 
ence between  the  bursting  pressure  of  the  boiler  and  the  bursting 
strength  of  the  boiler  shell.  The  former  indicates  the  reading  of 

J 


FIG.  78. — Standard  form  of  test  specimen. 

In  order  to  thoroughly  test  out  plate  material  for  boilers,  a  form  of  standard  specimen 
has  been  established  by  the  Boiler  Code  Committee  of  the  American  Society  of  Mechanical 
Engineers.  The  above  illustration  shows  the  standard  form  for  the  tension,  cold-bend,  and 
quench-bend  test  to  be  made  from  each  boiler  plate  as  rolled. 

the  steam  gage  at  which  the  bursting  will  take  place  while  the 
latter  indicates  the  unit  internal  pressure  in  the  boiler  material 
when  rupture  occurs. 

As  a  working  gage  pressure  for  boiler  operation  a  factor  of 
safety  of  5  is  often  used — that  is,  a  gage  pressure  ^i  that  of  the 
bursting  pressure  is  considered  as  the  largest  gage  pressure  that 
may  be  safely  put  upon  the  boiler.  It  should  be  noted  that  when 
considering  the  safety  of  a  boiler  we  always  deal  with  gage 
pressure  and  not  absolute  pressure.  The  bursting  pressure  of  a 
boiler  is  the  difference  between  the  pressure  inside  the  boiler  and 
the  pressure  outside,  when  rupture  would  occur,  and  as  the  latter 
is  always  the  pressure  of  the  atmosphere  the  bursting  pressure 
must  be  the  amount  the  inside  pressure  would  be  above  the 
atmospheric  pressure,  which  is  the  same  thing  as  gage  pressure. 

147 


148 


FUEL  OIL  AND  STEAM  ENGINEERING 


In  order  to  ascertain  the  breaking  strength  of  boiler  material, 
a  sample  known  as  a  standard  form  is  put  to  test.  Experiment- 
ally it  has  been  found  that  whether  a  piece  of  material  is  sub- 
jected to  rupture  by  tension,  compression,  or  shear,  the  unit  force 
required  to  rupture  a  square  inch  section,  is  equal  to  the  total 
force  observed  in  rupturing  the  specimen  in  each  particular  case 
divided  by  the  cross-sectional  area.  This  fundamental  law  enters 
largely  in  computation  of  boiler  strength.  Let  us  then  proceed 
to  this  analysis. 

The  Strength  of  the  Solid  Plate. — In  the  study  of  gases  and 
vapors  it  has  been  experimentally  established  that  the  pressures 
exerted  by  such  substances  are  felt  equally  in  all  directions  at  any 
given  point  under  consideration.  Let  us  then  consider  the  most 


FIG.  79. — A  diagrammatic  representation  of  internal  boiler  pressure. 

Since  the  pressure  of  a  vapor  is  exerted  equally  in  all  directions  we  should  consider  that 
direction  which  would  produce  the  most  active  results  in  tearing  apart  a  boiler  when  dee 
ducing  expressions  for  the  safe  working  pressure.  In  order  to  ascertain  the  total  pressur- 
tending  to  burst  the  riveted  section  shown  in  the  middle  figure  above,  the  pressure  should 
be  taken  with  the  direction  as  shown  by  the  arrows  in  this  figure. 

disastrous  direction  for  pressure  action.  This  evidently  would 
be  in  such  a  direction  as  would  tend  to  tear  the  boiler  shell  apart. 
If  the  length  of  shell  considered  be  of  length  p  equal  to  the  dis- 
tance from  center  to  center  of  the  riveted  section  or  what  is 
known  as  the  pitch  of  the  rivets,  we  have  for  a  boiler  of  thickness 
t  a  resisting  area  of  pt  sq.  in.  If  the  solid  shell  will  not  burst 
until  each  square  inch  of  area  has  upon  it  a  unit  force  of  St  pounds, 
the  total  resistive  force  according  to  the  experimental  law  stated 
in  the  previous  paragraphs  evidently  ptSf  Hence  if  A  is  the 
strength  of  solid  plate,  we  have 


A  =  tpSt 


(1) 


Rule  I.  Multiply  the  thickness  of  the  plate  by  the  pitch  of 
the  rivets  and  by  the  tensile  strength  of  the  plate.  The  result 
is  equal  to  the  strength  of  solid  plate. 


HOW  TO  COMPUTE  STRENGTH  OF  BOILER  SHELLS     149 

As  an  illustration  let  us  compute  the  strength  of  the  solid 
plate  for  a  boiler  whose  thickness  of  shell  is  J^  in.,  whose  spacing 
of  rivets  is  1%  in.,  and  whose  tensile  strength  stamped  upon  the 
boiler  plate  is  found  to  read  55,000  Ib.  per  square  inch. 

Applying  Rule  I,  we  have  that  the  strength  of  solid 
plate  is 

A  =  tpSt  =  0.25  X  1.625  X  55,000  =  22,343  Ib. 

The  Strength  of  the  Net  Section. — As  in  the  case  of  the  weakest 
link  determining  the  strength  of  the  chain,  so  the  strength  of  the 
boiler  shell  is  determined  by  its  weakest  section.  This  will 
evidently  be  at  the  point  where  the  shell  has  been  perforated 
for  the  insertion  of  rivets.  The  actual  area  that  will  resist 
rupture  is  now  no  longer  pt  but  since  it  has  been  weakened  by  an 
area  dt  wherein  d  represents  the  diameter  of  the  rivet  hole,  B,  the 
net  resistive  force  now  becomes 

B  =  (pt  -  dt)St  =  (p  -  d)tSt  (2) 

Rule  II  (a).  From  the  pitch  of  the  rivet  subtract  the  diameter 
of  the  rivet  hole,  then  multiply  by  the  thickness  of  the  plate 
and  again  by  the  tensile  strength  of  the  plate.  This  result  is 
equal  to  the  strength  of  the  plate  between  rivet  holes — in  other 
words  to  the  strength  of  the  net  section. 

Taking  as  an  illustration  the  same  boiler  mentioned  in  Rule 
I,  we  have,  if  the  diameter  of  the  rivet  hole  is  !^{Q  in.,  that  the 
strength  of  the  plate  B  between  rivet  holes  is 

B  =  (p  -  d)tSt  =  (1.625  -  0.6875)  0.25  X  55,000  =  12,890  Ib. 

Resistance  to  Shear. — A  boiler  may  not  only  fail  by  bursting 
apart  the  actual  shell  material  but  the  rivet  itself  may  give  way. 
Under  pressure  the  riveted  boiler  seam  may  pull  apart  and  cut  or 
shear  off  the  rivet  similar  to  the  action  that  would  take  place  by 
using  a  huge  pair  of  shears.  The  area  of  cross-section  of  the 
rivet  is  evidently  the  only  opposition  that  such  an  action  would 
receive  over  the  distance  between  one  set  of  rivets  in  case  of  a 
single  row  of  rivets,  or  if  there  be  n  rows  of  rivets,  the  area 
resisting  shear  is  n  times  that  for  a  single  row.  Hence,  the  force 
that  would  oppose  rupture  due  to  shear  is  evidently  n  (.7854d2)  S8, 
where  Ss  is  the  pounds  pressure  exerted  over  each  square  inch  of 
cross-section  under  shear.  From  results  shown  by  tests,  average 
iron  rivets  will  shear  at  38,000  Ib.  per  sq.  in.  in  single  shear  and 
76,000  Ibs.  in  double  shear;  steel  rivets  at  44,000  Ibs.  in  single 


150  FUEL  OIL  AND  STEAM  ENGINEERING 

shear  and  88,000  Ib.  in  double  shear.     Hence  we  have  that  the 
resistance  to  shear  C  for  a  riveted  section  is 

C  =  .7854d2n£8  (3) 

Rule  II  (6).  Multiply  the  area  of  the  rivet  (.7854d2)  by  the 
shearing  resistance  as  follows.  If  iron  rivets  in  single  shear,  allow 
38,000  Ib.  per  sq.  in.  of  section,  or  if  of  steel  allow  44,000  Ib.  per 
sq.  in.  If  the  resistance  is  in  double  shear  add  100  per  cent,  to 
the  above.  The  result  is  the  bursting  pressure  for  shear. 

Continuing  the  example  above  cited,  we  have  that  the  shearing 
strength  C  of  one  rivet  in  single  shear  is 

C  =  n  X  .7854d2S8  =  1  X  .7854  X  .68752  X  44,000  =  16,332  Ib. 

Resistance  to  Compression. — Again  the  rivet  may  be  forced 
to  give  way  by  having  its  longitudinal  section  (dt)  actually 
crushed  if  the  total  crushing  force  of  the  steam  pressure  exceed 
dtSc,  where  Sc  is  the  crushing  pressure  in  Ib.  per  sq.  in.  over  each 
unit  area  of  the  rivet.  Hence  the  resistance  to  compre'ssion  D  is 

D  =  dtSc  (4) 

Rule  II  (c).  Multiply  the  diameter  of  the  rivet  by  the  thick- 
ness of  the  boiler  plate  and  then  multiply  by  the  unit  bursting 
stress  for  compression  for  the  rivet,  which  is  taken  at  95,000  Ib.  per 
sq.  in.  The  result  is  equal  to  the  strength  of  the  rivet  section 
for  compression. 

The  resistance  to  compression  D  for  the  example  above  cited 
is  then 

D  =  dtSc  =  0.6875  X  0.25  X  95,000  =  16,328  Ib. 

The  Efficiency  of  the  Riveted  Section. — We  now  see  that  the 
riveted  section  weakens  the  solid  plate  in  three  ways.  In  the 


©  ©  O  O  O  © 


-5hearinq 
^ 


FIG.  80. — A  single  riveted  lap  joint  for  boiler  plates. 

By  taking  into  consideration  the  stresses  involved  in  a  sectional  distance  equal  to  the 
pitch  of  the  rivets,  P,  as  shown,  we  are  enabled  to  deduce  the  safe  working  gage  pressure 
for  boiler  operation. 

first  place,  the  boiler  may  give  way  more  easily  because  a  section 
equal  to  the  rivet  hole  has  been  cut  from  the  solid  plate.  In  the 
second  place,  the  rivet  may  be  actually  sheared  in  two,  and  in 
the  third  place,  it  may  be  crushed  longitudinally.  The  next 


HOW  TO  COMPUTE  STRENGTH  OF  BOILER  SHELLS     151 


thing  to  do  then  is  to  determine  the  ratio  that  each  one  of  these 
factors  bears  to  the  strength  of  the  solid  plate  and  adopt  the 
weakest  or  smallest  ratio  as  the  possible  point  where  rupture  will 
take  place.  Compute  these  three  efficiency  ratios  for  the  joint 
EJ  as  follows : 

B    =  C        D 

*      A'''~  A'      A 

Rule  III.  Divide  the  strength  of  the  weakest  section  by  the 
strength  of  the  solid  plate.  (See  Rule  I.)  The  result  is  the 
efficiency  of  the  riveted  section. 

Thus  in-  the  example  cited  we  have  seen  that  the  strength  of 
the  solid  plate  is  22,343  lb.,  that  its  strength  between  rivet  holes 
is  12,890  lb.,  that  the  shearing  strength  is  16,332  lb.  and  that  the 
crushing  strength  of  the  plate  in  front  of  one  rivet  is  16,328  lb. 
Hence,  the  weakest  place  is  in  the  strength  between  rivet  holes 
and  consequently  the  efficiency  of  point  EJ  is 

=        12<89°  =    .578. 


Gage  Pressure  Necessary  to  Burst  the  Solid  Boiler  Plate. — 

We  come  now  to  the  most  interesting  point  of  our  analysis, 
namely  to  compute  the  bursting  pressure  of  the  solid  plate. 


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FIG.  81. — A  double  riveted  lap  joint. 

By  introducing  a  number  of  rows  of  rivets  for  riveted  lap  joints  the  shearing  strength 
and  the  crushing  strength  of  the  riveted  section  are  proportionately  increased,  while  the 
tensile  strength  of  the  net  section  remains  the  same. 

In  the  discussion  of  the  strength  of  the  solid  boiler  plate  we 
found  that  the  force  of  steam  pressure  acting  so  as  to  tear  the 
boiler  plate  apart  longitudinally  would  evidently  prove  most 
disastrous  in  bursting  the  solid  boiler  plate.  Since  the  pressure 


152  FUEL  OIL  AND  STEAM  ENGINEERING 

of  steam  exerts  itself  equally  in  all  directions,  we  shall  compute 
the  total  pressure  available  in  this  particular  direction  as  this 
would  give  us  the  critical  pressure  for  our  present  consideration. 

If  the  boiler  is  of  length  1  in.  and  inner  diameter  -D  in.  the  area 
of  steam  pressure  is  Dl.  Since  now  the  boiler  gage  pressure  is 
P8  Ib.  per  sq.  in.,  the  total  pressure  of  the  steam  would  evidently 
be  Ps  Dl  Ib.  To  resist  the  boiler  tearing  apart  there  is  a  strip  of 
boiler  metal  on  each  side  of  length  Z  and  thickness  t.  Hence  the 
total  metallic  area  of  resistance  is  2lt.  If  now  the  force  of  re- 
sistance offered  by  the  metal  is  St  Ib.  per  sq.  in.,  we  have,  when 
an  explosion  or  bursting  apart  is  about  to  take  place,  that  this 
resistive  pressure  is  2ltSt. 

Equating  these  two  pressures,  we  have 

P8Dl  =  2'USt 

orP  2tSt          tSt  fto 

~D  =  D/2  (6) 

Thus  we  formulate. 

Rule  IV.  Multiply  the  thickness  of  the  plate  by  the  tensile 
strength  of  the  plate  and  divide  by  the  radius  (one-half  of  the 
diameter).  The  result  is  equal  to  the  bursting  pressure  of  the 
solid  plate. 

In  the  example  previously  cited  we  now  compute  the  bursting 
pressure  of  the  solid  shell  of  the  boiler  under  consideration  for  a 
boiler  diameter  of  36  in.  as  follows: 

tSt    _  025X55,000  _ 


s  ~  D/2  '  36/2 

This  means  that  a  gage  pressure  of  764  Ib.  per  sq.  in.  would 
rupture  the  given  boiler  if  it  existed  without  a  riveted  seam. 

Bursting  Pressure  of  the  Seam.  —  But  our  boiler  under  con- 
sideration would  evidently  burst  before  the  bursting  pressure 
of  the  solid'  plate  were  reached  for  the  riveted  section  has 
weakened  its  total  strength.  In  Rule  IV  we  found  that  the 
efficiency  of  the  riveted  joint  is  the  ratio  of  the  strength  of  the 
weakest  point  to  the  strength  of  the  solid  plate.  Hence  we  have 
that  the  gage  pressure  P  at  which  the  boiler  will  probably  rupture 
at  the  riveted  joint  is 

P  =  PsE,  (7) 

Rule  V.  Multiply  the  bursting  pressure  of  the  solid  plate  by 
the  efficiency  of  the  joint.  This  result  is  equal  to  the  bursting 
pressure  of  the  seam. 


HOW  TO  COMPUTE  STRENGTH  OF  BOILER  SHELLS     153 

Thus  since  the  efficiency  of  the  joint  E,  is  found  to  be  .578 
and  the  bursting  pressure  P8  of  the  solid  plate  to  be  764  lb.,  we 
have  that  the  bursting  pressure  P  of  the  joint  which  is  the  weakest 
part  of  the  boiler  construction  is 

p  =  PSE}  =  764  X  .578  =  442  lb. 


FIG.  82. — A  double  riveted  butt  and  double  strap  joint. 

In  general  the  butt  joint  doubles  the  shearing  strength  of  the  joint  while  the  net  tensile 
strength  and  the  crushing  strength  of  the  joint  remain  the  same  as  in  the  lap  joint  discussion. 

The  Safe  Working  Pressure.— Of  course  the  boiler  is  never 
allowed  to  operate  anywhere  near  this  bursting  pressure.  A 
factor  of  safety  is  insisted  upon.  The  U.  S.  tables  are  based 
upon  a  factor  of  safety  of  3 . 5  for  drilled  holes  and  4.20  for  punched 
holes,  which  are  the  lowest  factors  allowed  in  any  civilized  coun- 
try. The  factor  in  most  European  countries  is  either  5  or  6. 
In  any  case,  if  factor  of  safety /is  used,  we  have  that  the  working 
pressure  Pw  is  found  from  the  formula 


(8) 


The  rule  advised  by  the  Hartford  Insurance  Company's 
inspectors  is  as  follows: 

Rule  VI.  Divide  the  bursting  pressure  of  the  seam  by  the 
following  safety  factors:  0  to  125  pounds,  4.2;  from  125  to  150 
pounds,  4.5;  150  pounds  or  over,  5.  The  result  is  the  safe  working 
pressure  under  which  the  boiler  is  to  operate.  The  American 
Society  of  Mechanical  Engineers  in  their  Boiler  Code  require  a 
factor  of  safety  of  5  for  all  new  boilers. 


154  FUEL  OIL  AND  STEAM  ENGINEERING 

Thus  in  the  case  at  issue  the  safe  working  pressure  Pw  becomes 


Recapitulating  the  discussion  of  the  six  rules,  we  now  see  in  its 
completeness  the  method  involved  in  computing  the  safe  working 
pressure  of  a  boiler.  In  this  particular  instance  we  find  that  a 
boiler  of  36  in.  diameter,  with  J^  in.  plates  and  a  single  row  of 
rivets  spaced  1%  in.  apart  may  safely  operate  under  105  Ib. 
pressure  (gage). 

Example  of  a  Lap  Joint,  Longitudinal  or  Circumferential, 
Double-Riveted.  —  By  similar  reasoning  we  may  now  compute 
the  efficiency  of  a  lap  joint  which  is  double  riveted  whether 
longitudinal  or  circumferential.  Thus,  if  the  tensile  strength 
of  a  boiler  is  stamped  55,000  Ib.  per  sq.  in.  with  thickness  of  plate 
5^6  m->  pitch  of  rivets  2%  in.  diameter  of  rivet  hole  %  in.,  we 
have  by  applying  our  rules  : 

A  =  2.875  X  0.3125  X  55,000  =  49,414. 
B  =  (2.875  -  0.75)  0.3125  X  55,000  =  36,523. 
C  =  2  X  44,000  X  0.4418  =  38,878. 
D  =  2  X  0.75  X  0.3125  X  95,000  =  44,531. 
777      36,523 


CHAPTER  XX 


FURNACES  IN  FUEL  OIL  PRACTICE 


ET  us  now  set  forth  the  cycle  of 
operations  necessary  in  the  utili- 
zation of  crude  petroleum  as  an 
economic  factor  in  the  production 
of  steam.  The  oil  in  a  heated  state 
and  under  pressure  must  be  sprayed 
into  a  heated  compartment  or  fur- 
nace so  that  its  particles  are  in  fine 
globules  or  even  in  a  gaseous  state. 
Such  an  operation  is  known  as 
atomization  and  this  must  be  ac- 
complished in  an  efficient  and 

FIG.  83. — Interior  of  a  furnace,     .  u  u  r^,  , 

showing  brickwork  and  air-Spac-  thorough  manner.  Three  meth- 
ip-g-  ods  are  utilized  in  practice  to  accom- 

plish   this.     In    the   first   instance 

steam  under  pressure  is  mixed  with  the  oil  and  the  ingredients 
thus  shot  into  the  furnace.  In  the  second  instance  compressed 
air  is  used  to  accomplish  this  result,  and  in  the  third  instance, 
some  mechanical  device  or  physical  characteristic  of  the  oil  is 
made  use  of  to  whirl  or  thrust  the  oil  into  the  furnace  in  a  pul- 
verized or  atomized  state.  Literally  hundreds  of  inventions 
have  been  made  to  effect  the  atomization  of  oil.  It  is  to  be 
remembered,  however,  that  in  the  consideration  of  fuel  oil 
economy,  the  furnace  and  its  efficient  construction  are  after  all 
the  real  factors  that  go  toward  economic  fuel  consumption. 

Fuel  Oil  Furnace  Operation. — When  the  oil  is  atomized,  it 
must  be  brought  into  contact  with  the  requisite  quantity  of  air 
for  its  combustion,  and  this  quantity  of  air  must  be  at  the  same 
time  a  minimum  to  avoid  undue  heat  losses  that  may  be  carried 
away  in  the  outgoing  flue  gases.  To  accomplish  this  result 
the  checker  work  under  the  burners  that  control  the  admission 
of  air  must  be  properly  designed.  The  proper  quantity  of  air 
admission  as  a  whole  is  controlled  by  means  of  draft  regulation. 

155 


156 


FUEL  OIL  AND  STEAM  ENGINEERING 


An  illustration  of  how  this  may  be  sensitively  controlled  was 
shown  in  the  chapter  on  the  fundamentals  of  furnace  operation. 
To  accomplish  the  even  admission  of  air  into  the  furnace  the 
arrangement  of  the  check-board  of  brick-work  below  the  flame 
is  of  utmost  importance,  otherwise  unequal  heating  and  imperfect 
combustion  is  sure  to  follow.  Let  us  then  examine  a  chart 
formulated  by  E.  N.  Percy  of  the  Standard  Oil  Company's 
technical  staff,  shown  in  Fig.  84.  In  Fig.  1  of  this  chart  we  have 
a  fan-shaped  flame  with  openings  between  all  the  bricks.  The 
flame  does  not  cover  all  of  the  bricks,  hence,  no  matter  what  the 


FIG.  84. — Theoretical  display  for  brickwork  and  air-spacings. 

In  the  nine  illustrations  shown  above  are  graphically  displayed  the  behavior  of  the  fur- 
nace flame  and  the  formation  of  carbon  for  various  arrangements  of  air  spacings  below  the 
flame.  In  the  ninth  instance  a  theoretically  perfect  flame  is  obtained. 

conditions  are  there  will  be  an  excess  of  air  and  the  boiler  cannot 
work  economically  since  it  costs  as  much  to  heat  air  as  it  does  to 
heat  water.  Figure  2  shows  two  large  openings  under  the  middle 
of  the  flame;  such  a  flame  will  burn  hot  in  the  center  and  deposit 
carbon  in  the  corners  as  shown.  In  Fig.  3  we  have  a  large  opening 
under  the  flame  flow;  this  arrangement  will  cause  the  flame  to  tear 
and  burn  intensely  at  the  center  while  depositing  carbon  around 
the  corners,  as  well  as  allowing  cold  air  to  rise  and  strike  the  boiler 
directly.  The  large  opening  in  Fig.  4  allows  quantities  of  oil  to 
escape  over  the  flame;  intense  combustion  will  take  place  close  to 
the  burner,  thereby  over-heating  it,  and  at  the  same  time  the  flame 
will  be  irregular  and  ragged.  It  will  smoke  and  deposit  carbon  at 


FURNACES  IN  FUEL  OIL  PRACTICE 


157 


FIG.  85. — Arrangement  of  air-spaces  and  grate  bars  for  fuel  oil  practice. 

The  details  of  furnace  construction  have  more  to  do  with  efficient  operation  in  the  burn- 
ing of  fuel  oil  than  anything  else.  In  each  particular  installation  this  matter  should  re- 
ceive careful  attention.  In  the  illustrations  are  shown  the  plan  and  elevation  of  the  air 
spaces  and  grate  bars  for  the  Parker  boiler  installation  for  the  Fruitvale  Station  of  the 
Southern  Pacific  Co.  This  boiler  developed  an  evaporative  efficiency  of  83.69  per  cent, 
under  trial  test. 


FIG.  86. — A  former  type  of  furnace. 

In  this  view  the  floor  plan  of  a  back  shot  furnace  arrangement  is  shown.  The  burner  is 
set  in  a  recess  in  the  bridge  wall.  This  design  has  proven  of  high  order  in  central  station 
installations  of  the  West,  but  has  now  been  replaced  by  the  more  recent  type  shown  on  the 
following  page. 


158 


FUEL  OIL  AND  STEAM  ENGINEERING 


the  tips.  The  transverse  openings  between  all  the  bricks  as  shown 
in  Fig.  5  allows  at  all  times  a  great  excess  of  air  and  hence  are  not 
economic.  Figure  6  shows  draft  orifices  in  the  neighborhood  of 
the  burner;  such  a  flame  will  burn  clear  at  the  tips,  but  it  will  smoke 
and  deposit  carbon  near  the  burner.  The  longitudinal  slots  in 
Fig.  7  tend  to  tear  the  flame.  In  Fig.  8,  the  arrangement  gives  a 
broader  and  more  correctly  shaped  flame,  still  an  excess  of  air  is 
admitted  and  cold  air  allowed  to  pass  up  against  the  boiler  be- 
cause the  draft  slots  extend  beyond  the  end  of  the  flame.  Figure  9 


72-7 


JT 


E  LEV  AT /Of* 

FIG.  87. — An  excellent  furnace  arrangement. 


Here  is  an  excellent  furnace  arrangement  designed  for  a  524  hp.  boiler  with  standard 
low  setting.  The  checker  work  on  the  grate  bars  shown  in  shaded  area  represents  openings 
2M  by  3  in.  through  the  brickwork.  The  free  area  through  the  checker  work  is  2.44  sq.  in. 
per  hp.,  around  the  burner  0.62  sq.  in.  per  hp.,  making  a  total  free  area  of  3.06  sq.  in.  per  hp! 

approaches  more  nearly  to  the  correct  arrangement  of  bricks 
and  the  correct  shape  of  flame  for  a  flat  flame  furnace. 

An  excellent  furnace  is  shown  in  Fig.  87,  which  sets  forth 
the  floor  plan  of  a  back  shot  furnace  arrangement,  the  burner 
being  set  in  a  recess  in  the  bridge  wall.  The  recess  is  made  large 
enough  for  the  removal  of  the  burner  and  piers  of  fire  brick  are 
built  on  the  furnace  floor  in  front  of  the  recess  so  that  there  is  an 
opening  about  12  in.  by  9  in.  through  which  the  mixture  of  oil 
and  steam  enters  the  furnace  from  the  burner.  A  certain 


FURNACES  IN  FUEL  OIL  PRACTICE  159 

quantity  of  air  enters  through  the  same  opening,  being  drawn  in 
by  the  force  of  the  oil  and  steam.  A  bracket  is  provided  to  hold 
the  burner  at  the  center  of  the  opening. 

Air  openings  through  the  checker  work  on  the  grates  com- 
mence some  8  or  10  in.  from  the  burner,  the  number  of  openings 
and  the  width  increasing  gradually  until  about  2  ft.  from  the 
burner  the  openings  extend  across  the  full  width  of  the  furnace. 
There  are  no  openings  between  the  burners  near  the  bridge  wall 
so  that  no  air  can  enter  except  where  it  comes  in  contact  with  the 
atomized  oil.  The  fire  brick  piers  between  the  burners  become 
hot  and  assist  in  the  ignition  of  the  oil. 

The  distance  the  air  openings  are  extended  from  the  burners 
and  the  total  area  of  air  openings  depends  on  the  draft  available 
and  the  capacity  required  from  the  boiler.  With  a  draft  of  0.1 
of  an  inch  in  the  furnace  a  free  area  of  2^  sq.  in.  per  rated  boiler 
horsepower  through  the  checker  work  and  J^  sq.  in.  per  horse- 
power around  the  burner,  making  a  total  of  3  sq.  in.  per  horse- 
power, is  sufficient  to  operate  the  boiler  from  its  rated  capacity 
up  to  50  per  cent,  overload.  If  more  capacity  than  this  is 
required  either  a  greater  furnace  draft  must  be  provided  or  more 
openings  through  the  checker  work  must  be  installed  so  as  to 
increase  the  area.  The  amount  of  stack  draft  necessary  to 
maintain  0.1  of  an  inch  furnace  draft  depends  upon  the  type  of 
boiler  and  the  capacity  at  which  it  is  operated  as  this  will  deter- 
mine the  draft  loss  through  the  boiler.  The  loss  of  draft  between 
the  breeching  and  the  furnace  usually  runs  from  about  0.15 
of  an  inch  at  the  boilers'  rating  up  to  0.8  or  1  in.  at  double  rating. 

The  location  of  the  flame  can  be  varied  by  changing  the  height 
of  the  burner  above  the  checker  work,  this  height  usually  varying 
from  4  in.  to  8  in.  or  9  in.  The  character  of  the  flame  can  also 
be  varied  by  changing  the  distance  the  air  openings  extend  from 
the  burners.  It  is  customary  to  have  the  furthermost  air  open- 
ings about  4  or  5  ft.  distant  from  the  burner,  the  furnace  floor 
beyond  this  point  being  covered  with  solid  brick.  By  bringing 
the  air  openings  somewhat  farther  out  than  this  the  flame  can  be 
made  to  turn  up  or  by  having  the  air  openings  extended  out  a 
shorter  distance  the  flame  can  be  made  to  hug  closely  to  the  floor 
of  the  furnace. 

The  Commercial  Furnace. — Illustrations  are  shown  in  this 
article  that  set  forth  the  check-board  of  brick  work  for  air  admis- 
sion in  the  commercial  practice  of  boiler  economy.  Let  us  now 


160 


FUEL  OIL  AND  STEAM  ENGINEERING 


consider  all  the  principal  factors  that  must  be  considered  in  pick- 
ing an  efficient  type  of  commercial  furnace. 

The  furnace  must  be  constructed  of  such  heat  tested  brick- 
work that  it  will  stand  up  under  the  high  temperatures  developed 
and  the  refractory  material  of  which  it  is  composed  must  be  so 
installed  as  to  radiate  heat  to  assist  the  combustion  of  the  heated 
ingredients  of  the  fuel. 

This  combustion  must  be  entirely  completed  before  the 
gases  come  in  contact  with  the  heating  surfaces  of  the  boiler. 
Otherwise,  the  flame  will  be  extinguished,  possibly  to  unite  later 
in  the  flue  connection  or  in  the  stack.  This  means  that  ample 
space  must  be  provided  in  the  volumetric  proportions  of  the 


FIG.  88. — Plan    of    brickwork    and    air-spacings   in    marine    practice. 

In  the  practical  application  of  the  theoretical  deductions  for  proper  air  spacings,  commer- 
cial designers  differ  somewhat  from  the  theoretical  reasoning  involved.  In  this  illustration 
is  shown  the  brickwork  and  air-spacings  for  Scotch  marine  boilers  recommended  by  a  promi- 
nent company. 

furnace  to  insure  this  combustion  before  the  gases  begin  to 
travel  upward  against  the  boiler  surfaces. 

Finally,  there  must  be  no  localization  of  the  'heat  on  certain 
proportions  of  the  heating  surfaces  or  trouble  will  result  from 
overheating  and  blistering.  This  is  one  of  the  more  serious 
defects  that  had  to  be  overcome  in  the  earlier  days  of  fuel  oil 
practice.  The  burner  has  much  to  do  with  the  avoidance  of  this 
localization  activity. 

The  area  of  air  openings  through  the  checker-work  should  be 
made  of  sufficient  size  to  operate  the  boiler  at  the  maximum 
capacity  required  and  then  when  operating  at  lighter  loads  the 
air  supply  should  be  very  carefully  regulated. 


FURNACES  IN  FUEL  OIL  PRACTICE 


161 


Location  of  Burners. — The  simplest  form  of  oil  burning  furnace 
has  the  burners  entering  through  the  boiler  front,  the  flame  shoot- 
ing back  towards  the  rear  of  the  furnace.  This  is  the  most 


FIG.  89.— B.  &  W.  boiler  with  oil  burner  in  front. 

With  this  furnace  arrangement  the  flame  does  not  fill  out  the  first  pass,  so  the  front  end 
of  the  tubes  do  not  do  their  share  of  the  work. 

suitable  type  of  furnace  for  return  tubular  boilers  or  for  water 
tube  boilers  having  horizontal  baffles  such  as  Heine  or  Parker 
boilers. 

TfK 


FIG.  90. — B.  &  W.  boiler  with  Peabody  furnace. 

With  this  furnace  arrangement  the  gases  have  ample  volume  in  which  to  burn,  and  they 
distribute  themselves  over  the  entire  first  pass,  resulting  in  efficient  operation. 

For  water  tube  boilers  in  which  the  tubes  incline  downward 

toward  the  rear  and  having  vertical  gas  passages,  such  as  the 

11 


162 


FUEL  OIL  AND  STEAM  ENGINEERING 


Babcock  and  Wilcox  Boiler,  a  furnace  has  been  developed  in 
which  the  burner  head  is  placed  at  the  bridge  wall  and  the  flame 
shoots  forward  from  there.  This  furnace,  which  is  known  as  the 
Peabody  furnace,  was  the  result  of  an  extensive  series  of  tests 
made  by  Mr.  E.  H.  Peabody  in  California  some  years  ago. 

Owing  to  the  fact  that  the  tubes  are  inclined  downwards  toward 
the  rear,  the  Peabody  Furnace  gives  a  larger  furnace  volume  at 
the  end  of  the  furnace  farthest  from  the  burner.  This  is  of 


FiQ,  91. — Stirling  boiler  with  oil  burner  in  front. 

With  this  furnace  arrangement  the  tubes  are  swept  by  the  hot  gases  for  their  full  length, 
but  this  advantage  is  gained  at  the  expense  of  furnace  efficiency  owing  to  the  smaller  volume 
available  as  combustion  chamber. 

considerable  advantage  in  permitting  the  gases  to  expand  and 
cause  perfect  combustion.  Another  advantage  of  this  type  of 
furnace  with  the  B.  &  W.  boiler  is  that  the  flame  is  shot  forward 
and  comes  in  contact  with  the  front  end  of  the  tubes,  whereas 
with  the  burner  in  the  front  wall  the  gases  are  forced  back  close 
to  the  front  baffle  and  do  not  have  any  tendency  to  fill  the  front 
pass  of  the  boiler.  This  condition  is  illustrated  in  the  adjoining 
Figs.  89  and  90.  The  result  is  that  with  the  front  burner  arrange- 
ment a  considerable  portion  of  the  heating  surface  is  by-passed 
by  the  gases  and  is  therefore,  non-effective. 


FURNACES  IN  FUEL  OIL  PRACTICE 


163 


With  the  Stirling  boiler  excellent  results  are  obtained  either 
with  the  front  burner  arrangement,  or  with  the  burners  located 
at  the  bridge  wall.  With  the  former  arrangement  the  gases  come 
into  intimate  contact  with  the  boiler  heating  surface.  With  the 
latter  arrangement  a  very  large  furnace  volume  is  made  available, 
so  that  perfect  combustion  is  obtained  even  at  very  high  capaci- 
ties, and  as  the  front  tubes  absorb  a  large  amount  of  radiant  heat 
excellent  efficiencies  are  obtained.  With  a  four  pass  Stirling 


FIG.  92. — Stirling  boiler  with  Peabody-Hammel  furnace. 

This  furnace  arrangement  gives  a  splendid  furnace  with  large  volume.  The  gases  come 
in  contact  with  about  one-third  of  the  tubes  in  the  front  bank,  the  remainder  absorbing 
radiant  heat  direct  from  the  furnace. 

boiler  and  a  Peabody  furnace  still  better  results  are  obtained,  for 
in  this  type  of  boiler  there  are  fewer  tubes  exposed  direct  to  the 
fire,  and  the  gases  are  guided  down  among  the  remaining  tubes 
after  passing  the  first  baffle.  This  arrangement  therefore  gives 
a  combination  of  a  large  combustion  chamber  and  efficient  heat 
absorption. 

Service  For  One  Burner  Only. — Where  boilers  having  more 
than  one  burner  are  operated  at  very  light  loads  it  is  necessary 
at  times  to  have  only  one  burner  in  operation,  the  other  burner 
being  shut  off.  For  such  service  as  this  it  is  very  desirable  to 


164  FUEL  OIL  AND  STEAM  ENGINEERING 

have  the  ash  pit  divided  into  as  many  sections  as  there  are  burners 
so  that  when  one  burner  is  shut  off  the  ash  pit  door  opposite 
that  burner  can  be  closed  tight  and  no  air  from  the  other  ash 
pit  doors  will  enter  the  furnace  opposite  that  particular  burner. 
With  this  arrangement  it  is  possible  to  operate  a  large  boiler  at 
fractional  loads  and  still  maintain  fairly  good  economy.  This 
divided  ash  pit  is  one  of  the  patented  features  of  the  Hammel 


FIG.  93. — Babcock  &  Wilcox  boilers,  station  C,  Pacific  Gas  and  Electric  Com- 
pany, Oakland.  Boiler  is  set  three  feet  higher  than  the  standard  height  so  as 
to  provide  large  combustion  chambers  for  the  oil  furnace. 

Furnace,   which  is  similar  in  many  respects  to  the    Peabody 
Furnace. 

Large  Furnaces. — In  order  to  operate  oil  burning  boilers  at 
high  capacity  it  is  necessary  to  provided  ample  furnace  volume. 
With  the  usual  type  of  steam  atomizing  burner  it  is  possible  to 
burn  as  high  as  6  or  7  Ib.  of  oil  per  hour  per  cu.  ft.  of  furnace 
volume,  but  for  the  best  efficiency  the  quantity  should  not  exceed 
3  or  4  Ib.  per  hour  per  cu.  ft. 


FURNACES  IN  FUEL  OIL  PRACTICE 


165 


There  are  two  ways  by  which  the  furnace  volume  can  be  in- 
creased— one  by  lengthening  the  furnace  and  the  other  by  raising 
the  boilers.  In  Babcock  and  Wilcox  boilers,  a  larger  furnace 
can  often  be  obtained  by  moving  the  bridgewall  back  to  the  mud 
drum,  and  placing  the  burners  there.  This  gives  a  furnace  the 


—B 


FIG.  94. — The  Hammel  patent  oil  burning  furnace  with  boiler  raised  to  give  large 
combustion  chamber. 

full  length  of  the  tubes,  the  bottom  tubes  being  covered  with 
tile  from  the  rear  headers  to  the  front  baffle  to  prevent  the  gases 
by  passing  direct  to  the  third  pass  of  the  boiler. 

A  large  volume  Hammel  furnace,  obtained  by  raising  the  boiler 
a  few  feet  higher  than  the  standard  height,  is  shown  in  Fig.  94. 


CHAPTER  XXI 
BURNER  CLASSIFICATION  IN  FUEL  OIL  PRACTICE 

In  1902  and  1903  the  U.  S.  Naval  Fuel  Oil  Board  made  an 
exhaustive  inquiry  into  burners  of  various  types.  In  their  report 
a  classification  of  burners  was  set  forth  which  comprehensively 
details  the  fundamentals  of  various  types  of  burners  known  as  the 
drooling,  the  atomizer,  the  chamber,  the  injector,  and  the  projec- 
tor types. 

In  the  drooling  type  the  burner  allows  the  oil  to  drool  from  an 
upper  opening  down  to  a  lower  opening  from  which  the  steam  is 
issuing.  An  atomizer  burner  allows  the  oil  to  drop  directly  on 
the  steam.  The  chamber  or  inside  mixer  atomizes  the  oil  within 
the  burner  after  which  it  issues  from  an  orifice  of  the  desired 
form.  An  injector  burner  is  designed  primarily  to  operate  with- 
out a  pump  as  it  is  presumed  that  the  oil  will  be  sucked  from  the 
reservoir  by  the  siphoning  or  injector-like  action  of  the  steam  jet 
inside.  In  the  projector  burners  the  steam  blows  the  oil  from 
the  tip  of  the  burner. 

Two  other  general  classifications  prevail  depending  upon  the 
character  of  the  flame  emitted — namely,  the  fan  tail  and  the  rose. 
In  the  former  type  the  burner  produces  a  flat  flame  while  in  the 
latter  a  circular  flame  is  sent  forth. 

The  three  principal  types  of  burner  that  are  encountered  in 
central  station  practice  are,  however,  known  as  the  inside  mixer, 
the  outside  mixer,  and  the  mechanical  atomizer. 

The  Inside  Mixer. — In  burners  of  this  class,  the  steam  and 
oil  come  into  contact,  and  the  oil  is  atomized  inside  of  the  burner 
itself,  and  the  mixture  issues  from  the  burner  tip  ready  for  com- 
bustion at  once.  The  Hammel  burner  is  of  this  type. 

The  accompanying  Figure  95  illustrates  the  construction  of 
this  burner.  Oil  enters  at  A,  flows  through  D  into  the  mixing 
and  atomizing  chamber  C;  steam  enters  at  B,  passes  through  F, 
E,  and  then  through  three  small  slots,  G,  H  and  /,  into  mixing 
chamber  C  where  it  meets  the  oil,  and  as  these  small  steam  jets  cut 
across  the  oil  steam  at  an  angle,  the  energy  of  the  steam  is  utilized. 

166 


BURNER  CLASSIFICATION  IN  FUEL  OIL  PRACTICE    167 

The  burner  requires  for  its  operation  about  2  per  cent,  of  the 
steam  generated  by  the  boiler.     The  heavy  hydrocarbons  of  the 


FIG.  95. — The  inside  mixer  type  of  burner. 

In  burners  of  this  type  the  steam  and  oil  come  into  contact  and  the  oil  is  atomized  inside 
the  burner  itself.  The  mixture  then  issues  from  the  burner  tip  ready  for  combustion.  The 
Hammel  burner  shown  in  the  illustration  above  is  of  this  type. 

oil  are  atomized,  the  light  hydrocarbons  are  vaporized,  and  the 
completed  mixture  issues  from  the  burner  and  ignites  like  a  gas 


Fio.  96. — Typical  burners  and  control  pipes  ready  for  installation. 

flame.     In  normal  service  there  is  no  tendency  to  carbonize,  and 
the  only  way  in  which  carbonizing  can  be  caused  is  by  turning  off 


168 


FUEL  OIL  AND  STEAM  ENGINEERING 


the  steam  and  leaving  the  burner  filled  with  oil  instead  of  blow- 
ing it  out  before  shutting  down. 

All  oil  is  usually  more  or  less  gritty  and  will  cause  wear  of 
some  part  of  the  burner.  This  is  provided  for  in  the  Hammel 
burner — the  removable  plates  KK  can  be  quickly  replaced. 

The  Outside  Mixer. — In  the  outside  mixing  class  the  steam 
flows  through  a  narrow  slot  or  horizontal  row  of  small  holes  in 
the  burner  nozzle;  the  oil  flows  through  a  similar  slot  or  hole 
above  the  steam  orifice,  and  is  picked  up  by  the  steam  outside  of 
the  burner  and  atomization  thus  accomplished.  The  Peabody 
burner  is  typical  of  this  class.  It  will  be  noted  that  the  portions 
of  the  burner  forming  the  orifice  may  be  readily  replaced  in  case 
of  wear  or  if  it  is  desired  to  alter  the  form  of  the  flame. 


*Oil  Connection 

FIG.  97. — The  outside  mixer  type  of  burner. 

In  this  type  of  burner  the  steam  flows  through  a  narrow  slot  or  horizontal  row  of  small 
holes  in  the  burner  nozzle.  The  oil  flows  through  a  similar  slot  or  hole  above  the  steam  ori- 
fice and  is  picked  up  by  the  steam  outside  of  the  burner  and  thus  atomized.  The  Peabody 
burner  which  is  shown  in  this  illustration  is  a  typical  burner  of  this  type. 

There  are  many  other  makes  of  oil  burners  on  the  market, 
which  operate  on  the  same  principle  as  the  Hammel  or  the  Pea- 
body  burner.  A  few  of  these  are  illustrated  on  the  following 
pages,  Figures  98  to  106  inclusive. 

An  Example  of  the  Mechanical  Atomizer.— As  an  illustration 
of  one  of  the  many  interesting  types  of  burners  that  produce 
atomization  by  the  mechanical  process,  let  us  consider  for  the 
moment  the  rotary  burner  of  the  Fess  System  Company.  The 
mechanism  that  accomplishes  the  atomization  is  operated  by  a 
small  electric  motor  as  shown  of  Y±  to  J6  hp.  The  motor 
operates  a  rotary  pump  through  a  worm  gear.  This  pump  brings 
the  crude  oil  from  the  storage  tank  and  applies  it  to  the  burner, 
which  is  placed  in  the  center  of  the  fire  box.  The  burner  rotates 


BURNER  CLASSIFICATION  IN  FUEL  OIL  PRACTICE    169 

at  a  sufficient  speed  to  thoroughly  atomize  the  oil  by  centri- 
fugal force  and  by  the  proper  admission  of  air  a  smokeless  flame 
is  produced  equally  distributed  throughout  the  fire  box. 


FIG.  98. — The  Leahy  oil  burner. 

The  Leahy  burner  is  an  outside  mixer  and  is  made  either  for  the  back  firing  (Fig.  99)  or 
front  firing  (Fig.  98).  The  burner  equipment  includes  a  bypass  valve,  two  quick  action 
unions,  special  oil  regulation  valve  and  oil  strainer. 


FIG.  99. 


The  Home -Made  Type  of  Burner.— Patented  oil  burners  are 
practically  unknown  in  the  oil  fields.  Every  operator  makes  his 
own  burner  out  of  ordinary  fittings.  The  construction  varies 


170 


FUEL  OIL  AND  STEAM  ENGINEERING 


FIG.  100. — The  Witt  burner. 

This  is  an  outside  mixing  burner  with  removable  steel  tip.     The  above  illustration  shows 
backshot  burner  suitable  for  a  Peabody  furnace. 


FIG.  101. — Here  is  shown   a  Witt  inside  mixing  burner  for  front  firing. 


FIG.  102.— The  Tate-Jones  oil  burner. 

This  is  a  steam  atomizing  burner,  the  oil  being  controlled  by  a  needle  valve  in  the  burner 
head  and  the  steam  by  a  separate  valve  in  the  steam  pipe  near  the  burner.  The  length  of 
burner  and  size  of  opening  are  arranged  to  suit  each  particular  installation. 


BURNER  CLASSIFICATION  IN  FUEL  OIL  PRACTICE    171 

somewhat  depending  upon  the  ideas  of  the  maker  and  the  quality 
of  oil  burned.  The  general  principle  of  the  burner  is  illustrated 
in  Fig.  107.  No  oil  pumps  are  used,  the  oil  being  supplied  by 
gravity  from  a  tank  set  from  6  to  10  ft.  above  the  ground. 


FIG.  103. — The  W.  N.  Best  oil  burner. 

This  is  an  outside  mixing  burner,  the  oil  and  steam  leaving  the  burner  in  directions  at 
right  angles  to  one  another. 

An  important  peculiarity  of  the  burner  is  that  it  is  self -regulat- 
ing to  a  great  extent.  The  impact  of  the  jet  of  steam  issuing 
from  the  inner  pipe  produces  a  back  pressure  on  the  oil  issuing 
from  the  annular  space  between  the  pipes.  If  the  steam  valve 


OIL  OR  TAR 


FIG.   104. — W.  N.  best  burner. 

This  burner  is  provided  with  a  hinged  lip  which  may  be  raised  while  the  burner  is  operating, 
opening  up  the  steam  slot  so  that  it  can  be  blown  out,  thus  preventing  clogging.  This 
burner  can  be  used  with  either  steam  or  air  as  the  atomizing  medium. 

is  adjusted  for  good  atomization  any  increase  of  the  steam  pres- 
sure will  cause  more  steam  to  flow  through  the  inner  pipe.  This 
will  increase  the  back  pressure  at  the  tip  and  choke  back  the  oil 
coming  from  the  annular  space,  thus  decreasing  the  fire. 


172 


FUEL  OIL  AND  STEAM  ENGINEERING 


If,  on  the  other  hand,  the  steam  pressure  drops,  the  back 
pressure  at  the  tip  is  decreased,  more  oil  will  flow  and  the  fire 
will  be  increased. 


FIG.  105. — The  Wilgus  oil  burner. 

This  is  an  outside  mixing  burner  with  removable  tip  which  can  be  readily  changed  if  a 
different  shape  of  flame  is  desired.  The  burner  is  provided  with  oil  and  steam  regulating 
valves  interconnected  so  they  can  both  be  operated  by  one  lever.  This  insures  the  steam 
being  cut  down  to  suit  the  quantity  of  oil  used  at  light  loads. 


IOCKCTT  FLAT  fLtMt  OIL 


FIG.  106.— The  Lockett  flat  flame  oil  burner. 

This  is  an  outside  mixing  burner  with  renewable  tip.  A  feature  of  this  burner  is  the  com- 
bined regulating  valve  and  strainer  through  which  the  oil  must  pass  to  enter  the  burner. 
This  regulating  valve  lets  the  oil  out  through  a  slot  instead  of  the  annular  ring  that  occurs 
in  an  ordinary  globe  valve  when  partly  open.  The  slot  gives  an  opening  larger  than  the 
holes  in  the  strainer,  so  clogging  of  the  oil  burner  is  prevented.  The  strainer  can  be  readily 
removed  for  cleaning. 

This  type  of  burner  is  sensitive  to  variations  in  steam  pressure. 
As  the  steam  pressure  goes  up,  the  fire  is  cut  down  until  a  point 
is  reached  at  which  the  fire  becomes  spasmodic  or  "  bucks." 


BURNER  CLASSIFICATION  IN  FUEL  OIL  PRACTICE    173 

While  this  self  regulating  feature  helps  to  maintain  constant 
pressure  on  the  boiler,  it  is  not  economical  because  as  the  steam 
pressure  increases,  thus  diminishing  the  quantity  of  oil,  the 
quantity  of  steam  increases  with  the  pressure.  Thus,  the 
less  oil  is  burned  the  more  steam  is  used  for  atomizing,  which 
is  just  the  opposite  of  what  it  should  be. 


FIG.   107. — The  homemade  burner. 

This  ingenious  type  of  homemade  burner  is  a  product  of  the  oil  fields.  The  impact  of 
the  jet  of  steam  which  issues  from  the  inner  pipe  produces  a  back  pressure  on  the  oil  issuing 
from  the  annular  space  between  the  pipes,  thus  making  the  burner  self-regulating  to  a  great 
extent. 

Another  peculiarity  of  the  burner  is  that  it  will  begin  to  atomize 
when  the  steam  pressure  is  less  than  a  pound  above  atmosphere. 
As  soon  as  a  sizzle  is  heard  issuing  from  the  steam  pipe,  the  burner 
will  make  a  fairly  good  fire. 


CHAPTER  XXII 
MECHANICAL  ATOMIZING  OIL  BURNERS 

While  steam  atomizing  oil  burners  are  used  almost  exclusively 
in  stationary  power  plant  work  at  the  present  time,  the  mech- 
anical atomizing  oil  burner  has  found  great  favor  in  marine  work, 
and  is  the  standard  method  of  firing  oil  burning  marine  boilers. 

There  is  a  good  deal  of  interest  shown  at  present  in  the  use  of 
the  mechanical  atomizing  burner  in  stationary  plants,  and  it  is 
possible  that  it  may  eventually  entirely  displace  the  steam  atomiz- 
ing burner.  The  mechanical  atomizing  burner,  sometimes  called 


FIG.  108. — General  arrangement  Koerting  mechanical  oil  burning  system  on   a 

stationary  boiler. 

the  pressure  jet  burner,  is  made  in  a  number  of  different  forms 
all  of  which  operate  on  the  same  principle.  It  consists  essentially 
of  a  nozzle  containing  a  small  conical  shaped  orifice  through 
which  the  oil  is  forced  at  high  pressure,  the  oil  being  first  heated 
to  a  temperature  approaching  its  flash  point.  Inside  the  nozzle 
means  are  provided  to  give  the  oil  a  whirling  motion  of  sufficient 
intensity  to  make  it  fly  into  a  spray  on  account  of  the  centrifugal 
force  as  soon  as  it  leaves  the  nozzle.  The  burners  are  placed  in 
the  boiler  front  and  each  burner  is  provided  with  an  air  regulating 
device  which  admits  the  air  around  the  burner,  at  the  same  time 

174 


MECHANICAL  ATOMIZING  OIL  BURNER8  175 

regulating  the  quantity  of  air  to  suit  the  combustion  require- 
ments. In  some  makes  of  mechanical  burners  the  air  is  given  a 
twisting  motion  as  well  as  the  oil,  which  adds  to  the  effectiveness 
of  the  mixing  of  air  and  oil  for  combustion. 

There  are  so  many  different  makes  of  mechanical  atomizing 
burners  that  no  attempt  will  be  made  to  describe  them  all.  A 
brief  description  of  a  few  of  the  most  prominent  will,  however,  be 
of  interest. 

Koerting  Burner. — In  this  burner,  which  is  illustrated  on 
page  174  the  oil  is  given  a  rotary  motion  by  being  forced  through 
the  passages  of  a  helical  screw  into  a  small  conical  chamber 
containing  the  outlet  orifice.  The  air  enters  through  a  cylindrical 
chamber  having  openings  parallel  to  the  axis  of  the  burner,  and 
is  controlled  by  an  adjustable  cover  which  is  rotated  over  these 
openings. 

Dahl  Burner. — In  this  burner,  the  oil  is  given  its  rotary 
motion  by  passing  through  small  channels  formed  between  two 
parts  of  the  burner.  These  channels  deliver  the  oil  tangentially 
at  the  periphery  of  the  conical  chamber  in  the  tip,  through 
which  it  passes  in  the  form  of  a  vortex  to  the  orifice  outlet. 
The  air  is  controlled  by  the  furnace  doors,  and  the  mixture 
adjusted  by  a  conical  deflector  surrounding  the  burner. 

Peabody  Mechanical  Burner. — In  this  burner  the  rotary 
motion  is  secured  by  means  of  a  flat  disc  having  a  Y±  inch  hole, 
and  four  slots  which  lead  the  oil  tangentially  toward  this  central 
hole.  This  slotted  disc  fits  into  the  burner  tip  which  contains 
the  conical  chamber  and  orifice  outlet,  the  diameter  of  the  conical 
chamber  at  its  base  being  the  same  as  that  of  the  central  hole 
in  the  disc. 

With  this  burner  the  air  is  given  a  rotary  motion  as  well 
as  the  oil.  This  is  done  by  means  of  a  cast  iron  truncated 
cone  provided  with  blades,  in  the  center  of  which  is  placed  a 
so-called  impeller  plate,  also  bladed.  The  impeller  plate  gives  a 
rotary  motion  to  the  air  entering  close  to  the  burner,  and  the 
cone  gives  a  rotary  motion  to  the  air  entering  around  the  edge 
of  the  impeller  plate.  In  operation,  the  impeller  plate  and  the 
burner  may  be  moved  in  and  out  together,  being  fixed  in  re- 
lation to  each  other  but  adjustable  in  relation  to  the  truncated 
cone. 

Moore  Shipbuilding  Company  Burner. — In  this  burner  the  oil 
is  forced  through  slots  cut  longitudinally  on  the  outer  surface  of 


176 


FUEL  OIL  AND  STEAM  ENGINEERING 


a  plug,  the  slots  being  curved  at  the  end  to  give  the  necessary 
rotary  motion  to  the  oil  as  it  enters  the  conical  chamber  in  the 
burner  tip.  The  position  of  the  slotted  plug  in  relation  to  the 
burner  tip  may  be  adjusted  while  the  burner  is  in  operation  by 
means  of  a  rod  passing  through  the  burner. 

Coen  Burner. — In  this  burner,  which  is  illustrated  in  Fig.  109 
the  oil  is  delivered  to  the  central  chamber  by  means  of  small 
tangential  channels,  whose  area  can  be  altered  by 
means  of  a  rod  inside  the  burner  running  its  full 
length,  operated  by  the  hand-wheel  of  a  special 
angle  valve.  It  is  thus  possible  to  regulate  the 
fire  from  individual  burners  without  altering  the 
oil  pressure. 

The  main  air  supply  is  controlled  by  a  sliding 
plate  in  front  of  the  cylindrical  burner  chamber, 
and  a  sliding  cylinder  surrounding  this  chamber 
controls  a  secondary  air  supply. 

Draft. — Mechanical  atomizing  burners  operate 
satisfactorily  with  natural  draft  at  limited  capaci- 
ties, but  if  the  boilers  are  to  be  forced  much  above 
their  rated  capacity  it  is  necessary  to  equip  them 
with  forced  draft  fans,  delivering  the  air  under 
a  slight  pressure  to  the  burner  air  chambers. 

Pressure  and  Temperature  of  Oil. — The  opera- 
tion of  mechanical  atomizing  burners  varies  with 
both  the  pressure  and  temperature  of  the  oil. 
The  pressure  must  be  at  least  25  Ib.  in  order 
to  produce  good  atomization  and  it  may  be  in- 
creased up  to  200  Ib.  Pressures  higher  than  200 
Ib.  are  not  required  and  only  cause  unnecessary 
stress  of  the  oil  piping.  The  quantity  of  oil  burned 
is  regulated  by  varying  the  pressure  from  25  Ib. 
If  more  oil  is  required  than  can  be  obtained  at 
the  higher  pressure  it  is  necessary  in  most  makes  of  burner  to 
change  the  nozzles,  using  tips  with  larger  orifices.  If  less  oil  is 
needed  than  passes  through  the  burners  at  25  Ib.  pressure  it 
is  necessary  to  shut  off  some  of  the  burners. 

A  temperature  of  at  least  150°F.  is  required  to  properly  atomize 
the  oil.  The  atomization  is  improved  by  increasing  the  tempera- 
ture up  to  about  200°.  Above  this  temperature  no  change  is 
made  in  the  atomization  but  the  flame  becomes  shorter  and  the 


FIG.  109.— The 
Coen  mechan- 
ical atomizing 
burner. 

up  to  200  Ib. 


MECHANICAL  ATOMIZING  OIL  BURNERS 


177 


combustion  occurs  closer  to  the  burner  as  the  oil  is  heated  to  a 
higher  temperature.  As  the  oil  is  heated  the  first  effect  is  to 
reduce  its  viscosity  resulting  in  a  greater  quantity  of  oil  passing 
through  the  burner.  At  the  higher  temperatures,  however,  the 
increased  temperature  has  little  effect  on  the  viscosity,  but  owing 
to  the  increased  volume  of  the  oil  the  capacity  of  the  burner  is 
reduced. 

The  following  table  gives  the  quantity  of  oil  that  will  flow 
through  a  burner  having  a  KG  in.  diameter  orifice  at  a  pressure 
of  200  lb.,  the  oil  having  a  gravity  of  20°  Baume  and  a  flash 
point  of  220°F. : 


Temp.°F. 

Pounds  oil  per  hour 

Remarks 

60 

340 

No  atomization 

110 

440 

Bad  sparking 

153 

375 

Atomization  good 

210 

330 

Flame  white  and  short 

260 

300 

Flame  shorter 

304 

273 

Flame  2  ft.  long 

Advantages  of  Mechanical  Atomizing. — The  principal  advan- 
tage of  the  mechanical  atomizing  system  is  that  a  large  quantity 
of  oil  can  be  burned  in  a  furnace  of  a  given  volume. 

The  steam  atomizing  burner  as  applied  to  stationary 'boilers 
produces  a  flat  flame  and  the  combustion  occurs  on  the  upper 
and  lower  surfaces  of  this  flame,  with  the  result  that  a  consider- 
able proportion  of  the  volume  of  the  furnace  is  not  made  use  of. 

With  the  mechanical  atomizing  burner,  on  the  other  hand, 
there  is  what  may  be  called  volume  combustion,  the  mixture  of 
air  and  gases  occurring  throughout  the7  entire  furnace.  It  is 
therefore,  possible  to  completely  burn  more  oil  in  a  given  size 
of  furnace  by  this  method  than  by  the  steam  atomizing  method, 
or  if  the  same  quantity  of  oil  is  burned  in  both  cases  the  combus- 
tion with  the  mechanical  atomizing  system  will  be  more  complete 
in  the  furnace  proper,  so  that  the  flame  will  not  travel  so  far 
among  the  boiler  tubes  and  the  entire  efficiency  of  the  boiler  will 
be  greater.  The  cooling  of  the  gases  by  their  coming  in  contact 
with  the  boiler  tubes  before  the  combustion  is  completed  is  one 
of  the  principal  causes  of  low  efficiency  in  boilers  that  are  forced 


178 


FUEL  OIL  AND  STEAM  ENGINEERING 


MECHANICAL  ATOMIZING  OIL  BURNERS  179 

up  to  high  capacities,  and  any  method  of  combustion  that  pre- 
vents this  occurring  tends  to  improve  the  efficiency  of  the  boiler. 

The  maximum  quantity  of  oil  burned  by  steam  atomizing 
burners  amounts  to  6  or  7  Ib.  of  oil  per  hour  per  cu.  ft.  of  furnace 
volume,  whereas  with  mechanical  atomizing  burners  as  much  as 
11  or  12  Ib.  per  hour  per  cu.  ft.  has  been  burned. 

The  mechanical  atomizing  system  also  saves  the  steam  that  is 
used  in  the  steam  atomizing  system,  which  often  amounts  to 
3  per  cent,  or  4  per  cent,  of  the  total  steam  generated.  While 
some  additional  steam  is  required  in  the  mechanical  system  for 
heating  the  oil  up  to  the  higher  temperature  and  for  pumping  it 
to  the  higher  pressure,  the  condensation  or  exhaust  from  this 
steam  returns  to  the  feed  water  heater  so  that  the  quantity  uti- 
lized is  not  great.  The  loss  of  the  steam  used  by  the  steam  ato- 
mizing burner  is  of  much  greater  importance  for  marine  boilers 
than  for  stationary  boilers,  because  it  means  a  loss  of  fresh  water 
as  well  as  a  loss  of  steam.  It  is  for  this  reason  that  mechanical 
atomizing  burners  have  already  largely  displaced  steam  ato- 
mizing burners  on  board  ship. 

Disadvantages  of  Mechanical  Atomizing. — The  principal  dis- 
advantage of  the  mechanical  atomizing  burner  is  that  there  is 
aways  a  tendency  for  the  small  orifice  in  the  burner  to  choke 
up.  This  is  sometimes  due  to  grit  and  other  solids  in  the  oil 
which  pass  through  the  strainers  and  sometimes  due  to  carbon- 
ization on  account  of  the  flame  occurring  close  to  the  nozzle. 
To  overcome  this  difficulty  it  is  necessary  in  some  cases  to 
merely  slacken  back  the  feed  screw  of  the  burner  and  then 
readjust  it,  and  in  some  cases  to  turn-off  the  oil  altogether 
and  blow  steam  through  the  burner.  Whenever  the  fire  is 
burning  one  sided,  sparking  on  one  side  or  showing  black  streaks 
it  is  a  sign  that  the  burner  needs  cleaning.  As  the  number  of 
burners  required  for  mechanical  atomization  is  greater  than  for 
steam  atomization  this  difficulty  means  a  good  deal  of  careful 
attention  on  the  part  of  the  operator.  With  steam  atomizing, 
three  burners  are  sufficient  to  operate  a  large  800  h.p.  boiler, 
whereas  the  same  size  boiler  would  require  6  or  8  mechanical 
atomizing  burners. 

Another  objection  to  mechanical  atomizing  burners  for  sta- 
tionary power  plant  work  is  the  fact  that  the  air  supply  for  each 
burner  must  be  adjusted  separately  every  time  there  is  a  change  in 
the  quantity  of  oil  burned.  This  is  not  objectionable  where  there 


180  FUEL  OIL  AND  STEAM  ENGINEERING 

is  a  steady  load  as  occurs  on  board  ship,  but  in  a  stationary  power 
plant  where  the  load  is  changing  up  and  down  continuously  a 
continual  adjustment  of  the  air  supply  means  a  large  amount  of 
attention  on  the  part  of  the  fireman.  This  difficulty,  however, 
may  be  overcome  by  the  use  of  automatic  regulation  of  the  air, 
applying  to  mechanical  atomizers  the  same  principles  that  have 
already  proved  successful  in  the  automatic  regulation  of  steam 
atomizing  burners. 

Until  recently  the  use  of  mechanical  atomizing  burners  in  sta- 
tionary plants  has  been  confined  to  small  stations  operating  at  a 
fairly  steady  load,  such  as  the  pumping  stations  on  oil  pipe  lines. 
Recent  installations  have  proved  that  the  system  can  be  applied 
to  large  boilers,  and  is  desirable  especially  where  high  capacities 
are  required,  capacities  as  high  as  300  per  cent,  of  the  boiler 
rating  having  been  obtained.  It  must  be  realized,  however,  that 
the  use  of  this  system  for  variable  load  boilers  is  still  in  the  ex- 
perimental stage,  at  the  time  of  writing.  (April,  1920). 

Recent  research  along  the  lines  of  mechanical  atomization  by 
D.  S.  Jacobus  and  N.  E.  Lewis  is  of  great  importance  in  future 
development  of  steam  electric  generation,  where  oil  is  used  as 
fuel.  As  a  consequence,  in  the  following  pages  we  shall  set  forth 
in  full  the  data  presented  by  these  gentlemen  before  the  Pasadena 
Convention  of  the  National  Electric  Light  Association  in  May, 
1920,  on  this  timely  subject: 

The  practice  in  central  stations  of  running  boilers  up  to  300 
per  cent,  of  rating  in  carrying  peak  loads  has  made  it  necessary 
to  consider  some  other  means  of  burning  the  oil  than  with 
steam  atomizing  burners,  as  a  boiler  that  would  normally  be 
operated  over  peak  load  intervals  at  300  per  cent,  of  rating  or 
thereabouts  with  coal  could  not  be  operated  at  over  about  200 
per  cent,  of  rating  with  steam  atomizing  burners. 

The  limitation  of  capacity  with  steam  atomizing  burners  led 
the  Babcock  &  Wilcox  Company  to  make  a  series  of  tests  to 
develop  mechanical  atomizing  burners  of  the  type  used  in  marine 
practice  that  would  be  especially  adapted  to  stationary  boilers. 

The  tests  indicated  that  the  economy  obtainable  with  steam 
atomizing  and  with  mechanical  atomizing  oil  burners  at  the 
lower  capacities  was  about  the  same.  At  the  higher  capacities 
the  efficiency  with  the  mechanical  atomizing  burners  was  higher 
than  with  the  steam  atomizing  burners.  Considerably  higher 
capacities  could  be  obtained  with  the  mechanical  atomizing  burn- 


MECHANICAL  ATOMIZING  OIL  BURNERS 


181 


ers  than  with  the  steam  atomizing  burners.  The  results  of  com- 
parative tests  on  Babcock  &  Wilcox  boilers  are  shown  by  the 
curves  in  Fig.  Ill,  where  the  lower  curve  represents  the  net  effi- 
ciencies obtainable  at  different  ratings  with  steam  atomizing 
burners  and  the  upper  curve  the  corresponding  efficiencies  with 
mechanical  atomizing  burners.  By  net  efficiency  of  the  steam 
atomizing  burners  is  meant  the  efficiency  based  on  the  total 
steam  evaporated  less  the  steam  blown  to  waste  at  the  burners 
in  atomizing  the  oil.  In  the  case  of  the  mechanical  atomizing 
burners  no  deduction  is  made  for  the  relatively  small  amount  of 
steam  required  for  heating  and  pumping  for  the  mechanical 


50 


130 


2CO  250 

Per  Cent  Rating 


300 


350 


400 


FIG.  111. — A  relationship  showing  a  comparison  between  steam  atomization 
and  mechanical  atomization  of  fuel  oil  under  varying  boiler  efficiencies  and  per- 
centages of  rating. 

atomization  of  the  oil,  as  the  heat  in  this  steam  is  usually  returned 
to  the  system  by  employing  it  for  heating  the  oil  or  by  passing 
the  exhaust  steam  from  the  oil  pump  to  a  feed  water  heater. 

An  examination  of  the  curves  will  show  that  with  the  boilers 
operated  at  rating,  the  efficiency  in  each  case  is  in  the  neighbor- 
hood of  82  per  cent.  At  200  per  cent,  of  rating,  which  for  the 
usual  type  of  boiler  employed  in  large  boiler  plant  practice, 
represents  the  approximate  limit  of  capacity  for  steam  atomizing 
burners,  the  difference  in  efficiency  in  favor  of  the  mechanical 
atomizing  burner  is  in  the  neighborhood  of  6  per  cent.  At  high 
rates  of  driving,  feed-water  conditions,  as  will  be  discussed  later, 
have  a  very  important  bearing  on  th*e  maximum  that  can  be 


182  FUEL  OIL  AND  STEAM  ENGINEERING 

expected.  With  proper  feed-water  conditions,  using  mechanical 
atomizing  burners,  the  maximum  possible  capacities  are  as  high 
or  higher  than  are  being  obtained  with  forced  blast  stokers  over 
peak  load  periods  in  central  station  work. 

With  a  natural  draft  of  one  inch  available  the  capacity  with 
mechanical  atomizing  oil  burners  with  the  number  of  burners 
that  can  be  installed  in  the  ordinary  setting  for  coal  firing,  would 
be  limited  to  approximately  200  per  cent,  of  rating.  At  higher 
capacities  than  200  per  cent.,  forced  blast  at  the  burners  should 
be  used  with  mechanical  atomizing  burners. 

While  the  application  of  mechanical  atomizing  oil  burners 
to  stationary  boilers  is  still  in  the  development  stage,  the  tests 
made  by  Messrs.  Jacobus  and  Lewis  above  alluded  to,  together 
with  results  secured  at  several  plants  where  the  burners  have  been 
commercially  installed,  indicate  that  they  will  take  the  place  of 
steam  atomizing  burners  for  many  classes  of  service.  Mechanical 
atomizing  oil  burners  are  just  as  easy  to  operate  as  those  of  the 
steam  atomizing  type,  in  fact,  experience  in  marine  work  and  in 
the  few  installations  so  far  installed  for  stationary  boilers  has 
shown  that  they  are  less  likely  to  give  trouble  than  steam 
atomizing  burners.  There  is  less  trouble  through  carbonization 
or  clogging  up  and  when  a  burner  has  to  be  changed  less  time  is 
required  for  a  mechanical  atomizing  burner  than  for  a  steam 
atomizing  burner. 

Where  a  change  is  made  from  coal  to  oil  firing  the  mechanical 
atomizing  oil  burners  are  especially  adapted  as  in  many  cases 
the  stokers  can  be  protected  with  brickwork  and  the  oil  burned 
directly  above  the  stokers  without  removing  the  stokers.  By 
keeping  the  stokers  in  place  the  boilers  can  readily  be  converted 
back  to  coal  firing  if  desired.  The  same  blast  that  is  used  for 
forced  draft  stokers  may  be  employed  for  the  mechanical  atomiz- 
ing burners,  thereby  saving  the  expense  of  a  portion  of  the  oil 
burning  equipment. 

The  reason  that  higher  capacities  are  available  with  mechanical 
atomizing  burners  than  with  steam  atomizing  burners  is  on  account 
of  the  quicker  combustion  secured  with  the  mechanical  atomizing 
burners  and  because  the  steam  atomizing  burners  do  not  utilize 
the  full  furnace  volume.  With  mechanical  atomizing  burners 
the  oil  is  expelled  under  a  heavy  pressure  from  the  burner  tips 
in  a  fine  mist  and  intimately  mingled  with  the  air  for  combustion 
directly  at  the  burners,  which  leads  to  the  greater  part  of  the  oil 


MECHANICAL  ATOMIZING  OIL  BURNERS  183 

being  consumed  in  short  cone-shaped  flames.  With  steam  atomiz- 
ing burners  the  oil  is  not  divided  into  anywhere  near  as  fine  a 
spray  and  there  is  no  quick  and  thorough  mingling  of  the  oil  and 
air,  which  leads  to  the  long  flames  characteristic  of  the  type. 
To  secure  a  good  combustion  with  steam  atomizing  burners  the 
flames  should  have  a  natural  path  of  travel,  the  air  for  combustion 
being  admitted  beneath  the  flames.  It  can  be  readily  appre- 
ciated that  only,  say,  one-half  of  the  total  furnace  volume  may  be 
occupied  by  the  flames  with  steam  atomizing  burners  and  that 
much  of  the  furnace  volume  may  be  ineffective.  With  the 
mechanical  atomizing  burners  there  are,  therefore,  two  effects 
which  lead  toward  a  greater  capacity  being  developed  with  a 
given  furnace  volume,  the  first  being  the  quickness  of  combustion 
due  to  the  better  atomization  and  thorough  mingling  of  the  oil 
and  air  at  the  burners,  and  the  second  the  form  of  the  flames  which 
make  available  a  greater  proportion  of  the  furnace  volume. 

In  marine  practice  the  furnace  must  necessarily  be  kept  down 
to  the  minimum  size  that  can  be  employed  in  order  to  save  space 
and  the  best  commercial  results  are  secured  by  so  proportioning 
the  furnace  that  a  good  efficiency  will  be  secured  at  the  ordinary 
loads  carried,  or  at  cruising  speeds,  with  the  burners  arranged  so 
that  in  an  emergency  the  boiler  may  be  run  at  a  considerably  high- 
er capacity.  In  land  work  where  every  cu.  ft.  of  space  occupied 
need  not  be  considered  as  carefully  as  in  marine  work,  it  is  obvi- 
ous that  a  furnace  can  be  installed  to  advantage  of  a  larger  size 
than  in  marine  work.  Again,  in  stationary  work  poor  feed  water 
has  often  to  be  contended  with,  and  with  poor  feed  water  a 
larger  volume  assists  materially  in  reducing  the  tube  losses. 
Experience  with  oil  burners  has  indicated  that  for  a  given  over- 
load capacity  there  will  be  more  tube  difficulties  in  case  the  feed 
water  is  not  thoroughly  clean  than  with  a  properly  arranged  coal 
fired  furnace.  This  comes  through  the  higher  furnace  tempera- 
ture with  oil  firing,  which  leads  to  a  higher  absorption  rate  in  the 
tubes  which  come  next  the  furnace.  With  poor  feed  water  oil 
fired  boilers  must  be  operated  at  a  lower  rating  than  coal  fired 
boilers  if  tube  difficulties  are  to  be  minimized,  and  in  some  cases 
it  may  be  desirable  not  to  run  at  an  average  load  of  very  much 
over  rating. 

To  run  at  the  higher  capacities  great  care  must  be  exercised 
in  the  operation.  An  entirely  different  field  is  entered  when 
capacities  are  carried  of  300  per  cent,  or  over,  and  it  would  be 


184  FUEL  OIL  AND  STEAM  ENGINEERING 

folly  to  attempt  to  operate  at  these  capacities  without  most  com- 
petent operators,  clean  feed  water  and  the  strictest  attention  to  all 
details. 

In  marine  practice  the  make-up  water  is  distilled.  The 
make-up  water  in  some  stationary  plants  is  now  distilled,  and 
as  this  can  be  done  without  any  material  loss  of  heat  to  the  sys- 
tem, it  is  a  practice  which  undoubtedly  will  be  followed  to  a 
greater  extent  in  the  future.  The  use  of  mechanical  oil  burners 
reduces  the  amount  of  make-up  water  required  through  eliminat- 
ing the  loss  of  the  steam  that  is  blown  to  waste  with  steam 
atomizing  burners.  Where  the  make-up  water  is  secured  from 
an  evaporator  it  is  obviously  advantageous  to  use  mechanical 
atomizing  burners  to  reduce  the  amount  of  make-up  water  re- 
quired. This  element  has  an  important  bearing  on  the  use 
of  mechanical  atomizing  burners  for  marine  work. 

Where  steam  atomizing  burners  are  used  in  connection  with 
a  boiler  fitted  with  an  economizer  the  steam  carried  away  in  the 
flue  gases  increases  the  tendency  to  condense  a  portion  of  the 
vapor  from  the  flue  gases  on  the  colder  parts  of  the  economizer, 
thereby  producing  a  sweating  action  on  the  exterior  of  the 
economizer.  Mechanical  atomizing  oil  burners  are  preferable 
in  this  respect  as  they  do  not  add  any  steam  to  the  gases. 

The  mechanical  atomizing  oil  burners  that  have  been  de- 
veloped and  patented  by  the  Babcock  &  Wilcox  Company  for 
stationary  work  are  shown  in  Figs.  112  and  113. 

Fig.  112  shows  a  Babcock  &  Wilcox  mechanical  atomizing  oil 
burner  of  the  Lodi  design  for  use  without  a  forced  draft  and  Fig. 
1 13  the  same  burner  for  use  with  a  forced  draft.  The  correspond- 
ing parts  are  similarly  numbered  in  each  of  the  two  figures. 

The  fire  brick  moulded  tile  (1)  are  held  in  place  by  the  cast 
iron  grid  (2) .  The  cast  iron  bladed  cone  (3)  conducts  the  air  and 
atomized  oil  to  the  furnace.  The  main  register  casting  (4)  is 
bolted  through  the  boiler  front  plate  to  the  cast  iron  grid  (2), 
thus  holding  the  cone  (3)  in  place.  The  main  register  casting  (4) 
is  fitted  with  four  automatic  air  doors  (5),  by  the  use  of  which 
the  quantity  of  air  supplied  to  the  burner  may  be  regulated  or 
shut  off  entirely  if  desired.  These  doors  are  so  designed  that 
they  will  close  automatically  in  case  of  a  flare-back  in  the  furnace 
or  the  bursting  of  a  boiler  tube,  thus  protecting  the  fireman  who 
may  be  standing  in  front  of  the  boiler. 

To  the  front  of  the  register  casting  is  fastened  a  cover  plate  (6) , 


MECHANICAL  ATOMIZING  OIL  BURNERS 


185 


this  cover  plate  being  secured  with  studs  to  the  main  register 
casting  and  holding  in  place  the  radiation  guard  (19)  and  the 
spider  casting  (7).  In  case  a  double  front  is  used  for  forced 
blast  the  radiation  guard  is  replaced  by  the  outer  front  plate  of 
the  double  front,  as  shown  in  Fig.  3. 

The  spider  casting  (7)  has  four  cams  which  control  the  opera- 
tion of  the  automatic  air  doors  (5).  Fastened  to  the  spider 
casting  (7)  and  passing  through  a  slot  in  the  coverplate  (6)  is  a 
handle  (8)  to  operate  the  spider.  By  moving  the  handle  (8)  to 
the  extreme  right  the  air  doors  are  all  closed,  and  by  moving  it  to 
the  left  the  doors  are  gradually  opened. 


1  Fire  Brick  Moulded  Tile 

2  Grid  for  Holding  Tile 

3  Bladed  Cone 

4  Main  Register  Casting 

5  Automatic  Air  Doors 

6  Cover  Plate 

7  Spider  with  Cams 

8  Handle  for  Locking  Sridcr 

9  Distance  Piece 


10  Quick  Detachable  Coupling 

11  Quick  Detachable  Yoke 

12  Mechanical  Atomizer 

13  Bolt  for  Setting  up  Ground  Joint 

14  Hinge 

15  Center  Impeller 
18  Wing  Set  Screw 

17  Headless  Set  Screw 

18  Flexible  Oil  Connection 
20  Radiation  Guard 


FIG.   112. — The   Babcock  and  Wilcox  mechanical  oil  burners  showing  single 
front  construction  for  natural  draft. 

Passing  through  the  center  opening  in  the  cover  plate  (6) 
is  a  distance  piece  (9),  to  the  outer  end  of  which  is  fastened  a 
quick  detachable  coupling  (10)  and  yoke  (11). 

To  the  other  end  of  this  distance  piece  is  fastened  an  aluminized 
steel  conical  shaped  impeller  plate  (15)  for  regulating  the  dis- 
tribution of  air  at  the  nozzle  of  the  burner.  Passing  through  the 
distance  piece  (9)  is  the  mechanical  atomizer  (12),  this  atomizer 
being  held  in  place  and  connected  to  the  fuel  oil  supply  line 
through  the  quick  detachable  coupling  (10)  and  yoke  (11),  thus 
making  the  atomizer  (12),  the  distance  piece  (9),  and  the  center 
impeller  (15)  a  rigid  unit  when  in  operation. 


186 


FUEL  OIL  AND  STEAM  ENGINEERING 


The  distance  piece  (9)  is  so  designed  that  it  may  be  moved 
along  its  axis,  thus  moving  the  impeller  plate  (15)  in  and  out 
with  reference  to  the  balded  cone  (3),  and  decreasing  or  enlarging 
at  will  the  clear  area  for  the  passage  of  air  around  the  outside 
of  the  impeller  plate. 

By  means  of  a  set  screw  (16)  the  impeller  plate  (15),  together 
with  distance  piece  (9)  and  atomizer  (12)  may  be  fastened  in 
any  desired  position.  To  adjust  the  distance  between  the  tip 
of  the  atomizer  (12)  and  the  center  opening  in  the  impeller  plate 
(15),  a  headless  set  screw  (17)  is  unscrewed,  then  by  holding  the 


Boiler  Front 
^Plate 


Lighting  &.  Observation  Door, 


1  Fire  Brick  Moulded  Tile 

2  Grid  for  Holding  Tile 

3  Bladed  Gone 

4  Main  Register  Casting 

5  Automatic  Air  Doors 

6  Cover  Plate 

7  Spider  with  Cams 

8  Handle  for  Locking  Spider 

9  Distance  Piece 


10  Quick  Detachable  Coupling 
U  Quick  Detachable  Yoke 

12  Mechacical  Atomizer 

13  Bolt  for  Setting  up  Ground  Joint 

14  Hinge 

15  Center  Impeller 
18  "Wing  Set  Screw 

17  Headless  Set  Screw 

18  Flexible  Oil  Connection 
20  Spacing  Collar 

FIG.  113. — The  Babcock  and  Wiicox  mechanical  oil  burners  showing  double 
front  construction  for  forced  draft. 

distance  piece  (9)  with  the  set  screw  (16),  the  coupling  (10) 
may  be  rotated  on  the  distance  piece  (9)  to  bring  it  to  any  posi- 
tion desired. 

The  distance  between  the  tip  of  the  atomizer  (12)  and  the 
central  opening  in  the  impeller  plate  (15)  should  be  maintained 
at  approximately  ^  inch,  and  when  the  coupling  (10)  is  moved 
up  on  the  distance  piece  (9)  sufficiently  to  give  this  distance, 
the  headless  set  screw  is  driven  home. 

In  Fig.  113  a  spacing  collar  (20)  is  shown  which  is  used  when  the 
number  of  burners  is  such  that  the  outer  front  plate  must  be 
moved  out  to  give  the  proper  flow  area  for  the  air  supplied  to  the 
burners  by  means  of  the  forced  draft. 


MECHANICAL  ATOMIZING  OIL  BURNERS  187 

The  curve  in  Fig.  Ill  for  the  efficiency  secured  at  different 
ratings  with  steam  atomizing  burners  is  based  on  tests  that  were 
made  on  a  14-high  B.  &  W.  boiler  in  1907  at  the  Redondo  plant 
of  the  Pacific  Light  &  Power  Company.  In  these  tests  California 
oil  of  about  14°  Baume  was  burned  which  has  a  heat  of  combus- 
tion of  approximately  18,000  B.t.u.  per  pound. 

The  curve  for  mechanical  atomizing  oil  burners  shown  in 
Fig.  Ill  is  based  on  tests  made  on  a  14-high  B.  &  W.  boiler  at  the 
Bayonne  works  of  the  Babcock  &  Wilcox  Company  with  Mexican 
oil  14  to  16°  Baume,  having  a  heat  of  combustion  of  approxi- 
mately 18,300  B.t.u.  per  pound.  The  conditions  existing  in  the 
tests  of  the  mechanical  atomizing  burners  were  as  follows: 

The  oil  pressure  at  the  burner  varied  from  100  to  200  Ibs.  per 
sq.  in.,  depending  on  the  capacity  at  which  the  boiler  was  oper- 
ated and  upon  the  size  of  the  sprayer  or  orifice  plates  which  are 
used  inside  the  tip  of  the  mechanical  atomizers.  The  best  at- 
omization  was  obtained  when  the  oil  was  heated  to  give  a  vis- 
cosity of  from  3°  to  5°  Engler,  which  required  a  temperature  of 
from  220°  to  250°F.  Live  steam  was  used  for  heating  the  oil 
from  about  110°  to  the  temperature  specified,  the  amount  ap- 
proximating one  half  of  one  per  cent,  of  the  total  steam  generated. 

In  the  tests  the  amount  of  steam  required  for  driving  a  rotary 
pump  which  was  used  for  pumping  the  oil  amounted  to  from  1 
to  lj/2  per  cent,  of  the  total  steam  generated.  The  pump  was 
considerably  larger  than  required  and  therefore  wasteful.  In  a 
large  plant  the  amount  of  steam  required  for  pumping  the  oil 
would  be  in  the  neighborhood  of  J^  of  1  per  cent,  of  the  total 
steam  generated  and  the  exhaust  steam  from  the  pump  could  be 
used  for  the  preliminary  heating  of  the  oil. 

The  number  of  burners  for  use  in  a  given  boiler  may  be  de- 
termined on  the  basis  of  one  burner  per  120  to  130  rated  boiler 
h.p.  This  capacity  may  be  exceeded  in  certain  instances. 

The  variation  in  load  is  taken  care  of  by  adjusting  the  oil 
pressure  at  the  pump  between  the  limits  of  100  to  200  Ib.  per  sq. 
in.  and  by  cutting  burners  in  and  out.  Throttling  the  oil  at  any 
individual  burner  should  not  be  done  and  a  valve  to  a  given  burn- 
er should  remain  always  wide  open  or  tight  shut. 

It  is  not  advisable  to  attempt  to  regulate  the  air  to  any  great 
extent  with  the  air  doors  on  individual  burners.  The  best  way 
to  adjust  the  air  is  through  the  use  of  the  boiler  dampers  for 
natural  draft  installations.  Where  a  forced  draft  is  employed 


188  FUEL  OIL  AND  STEAM  ENGINEERING 

the  air  is  regulated  through  the  use  of  the  boiler  dampers  and  the 
adjustment  of  the  air  blast. 

A  boiler  fitted  with  mechanical  atomizing  burners  requires 
more  draft  to  operate  it  at  a  given  rating  than  one  fitted 
with  steam  atomizing  burners,  as  the  air  for  combustion  must  be 
drawn  through  the  burner  registers  at  a  velocity  that  will  cause 
it  to  mingle  intimately  with  the  atomized  oil.  With  no  forced 
draft  the  amount  of  draft  suction  required  at  the  damper  of  a 
14-high  B.  &  W.  boiler  for  drawing  the  air  through  the  burner 
registers  and  for  drawing  the  gases  through  the  boiler  when 
operating  at  rating,  150  per  cent,  of  rating,  200  per  cent,  of 
rating  and  250  per  cent,  of  rating  is  0.25,  0.6,  1.0,  and  1.65  in. 
water  column,  respectively.  Where  a  forced  draft  is  used  at  the 
burners,  the  draft  suction  required  at  the  boiler  damper  to  over- 
come the  resistance  of  the  gases  flowing  through  the  boiler  is 
0.15,  0.20,  0.35,  and  0.50  in.  water  column,  respectively,  and  when 
operated  at  250  per  cent,  of  rating  the  forced  draft  required  at 
the  burners  is  1.15  in.  water  column. 


CHAPTER  XXIII 

RULES    FOR    EFFICIENT    OPERATION    OF    OIL    FIRED 

BOILERS 

Since  the  advent  of  steam  turbines  the  relative  importance 
of  the  fireroom  crew  as  a  factor  in  economical  operation  has  in- 
creased considerably  compared  with  the  engine-room  crew. 
This  is  because  the  steam  turbine,  after  it  has  once  been  properly 
set  up,  operates  continuously  at  a  fixed  steam  consumption  for  a 
given  load  and  nothing  can  be  done  to  improve  its  economy  other 
than  to  keep  the  turbine,  condenser  and  auxiliaries  clean  and  in 
good  operative  condition.  In  the  boiler  room,  on  the  other  hand, 
continual  watchfulness  is  necessary  to  keep  the  boilers  operating 
at  good  efficiency,  and  the  slightest  laxity  in  attention  to  the 
various  details  results  in  a  large  waste  of  fuel.  To  assist  the  opera- 
tors of  oil-fired  boilers  in  obtaining  the  best  economy  possible, 
the  writers  have  prepared  the  following  set  of  rules,  which  if 
carefully  followed  will  bring  the  daily  operating  efficiency  of  the 
plant  very  close  to  test  results: 

1.  Regulate  Air  to  Suit  Load. — The  regulation  of  the  air  supply 
is  one  of  the  most  important  things  in  the  operation  of  oil-fired 
boilers.  If  there  is  not  enough  air,  a  great  waste  of  fuel  may 
occur  as  part  of  the  atomized  oil  will  simply  pass  up  the  chimney 
unburned.  On  the  other  hand,  it  is  possible  to  waste  just  as 
much  fuel  by  allowing  too  much  air  to  enter  the  furnace  as  all  of 
the  extra  air  is  heated  up  and  passes  out  at  the  temperature  of 
the  chimney  gases,  carrying  away  with  it  an  enormous  amount  of 
heat.  To  determine  accurately  the  amount  of  air  required  for  the 
best  conditions  it  is  necessary  to  analyze  the -flue  gases. 

Many  plants,  however,  are  not  provided  with  the  apparatus 
necessary  for  this,  and  in  such  cases  the  air  may  be  regulated  with 
a  fair  degree  of  accuracy  by  an  observation  of  the  smoke  dis- 
charged from  the  stack.  For  perfect  combustion  there  should  be 
no  smoke,  and  if  any  smoke  appears  it  means  incomplete  com- 
bustion and  not  enough  air.  If  there  is  no  smoke,  however,  it 
does  not  follow  that  the  conditions  are  right,  as  no  smoke  may 
mean  either  just  the  right  amount  of  air  or  a  large  excess  of  air. 

189 


190 


FUEL  OIL  AND  STEAM  ENGINEERING 


c«   ft 


EFFICIENT  OPERATION  OF  OIL  FIRED  BOILERS        191 

To  properly  regulate  the  air,  therefore,  if  the  boiler  is  operating 
with  no  smoke  the  damper  should  be  gradually  closed  until 
light  gray  smoke  just  begins  to  appear;  if  then  the  damper  is 
opened  very  slightly,  this  smoke  will  be  barely  perceptible  and 
the  conditions  for  the  most  economical  operation  will  be  obtained. 

2.  Prevent  Air  Leakage  Through  Setting. — Air  leaks  may  be 
detected  by  holding  a  candle  flame  at  the  cracks  in  the  boiler 
setting.     If  the  flame  is  drawn  in,  it  shows  that  there  is  an  air 
leak  which  should  be  stopped  up  as  far  as  possible. 

A  good  coat  of  fire-resisting  paint  over  a  brick  setting  is  a 
good  investment,  for  the  bricks  themselves  are  quite  porous  as 
can  be  demonstrated  by  dropping  one  in  water  and  noting  the 
air  bubbles  driven  from  it. 

There  are  two  ways  by  which  the  air  can  be  regulated,  namely, 
by  the  damper  at  the  outlet  of  the  boiler  or  by  the  ash-pit  doors. 
If  the  air  is  regulated  by  the  ash-pit  doors,  the  damper  being  left 
wide  open,  there  will  be  a  strong  draft  within  the  setting,  tending 
to  cause  air  to  leak  in  through  the  cracks  in  the  brickwork.  The 
strong  draft  also  tends  to  pull  the  gases  through  the  setting  by 
the  shortest  paths,  so  that  some  of  the  heating  surface  is  not 
swept  by  the  gases. 

If,  on  the  other  hand,  the  ash-pit  doors  are  left  wide  open  and 
the  air  is  regulated  by  partly  closing  the  damper,  the  draft  in- 
side the  boiler  setting  is  very  slight  so  that  the  air  leakage  is 
reduced  to  a  minimum.  There  is  little  force  tending  to  change 
the  direction  of  the  flow  of  the  gases  so  that  they  travel  of  their 
own  momentum  to  the  furthermost  corners  and  fill  out  the  set- 
ting completely,  thus  coming  in  contact  with  all  the  heating  sur- 
face of  "the  boiler.  It  is,  therefore,  much  better  to  regulate  the 
air  by  means  of  the  damper  than  by  means  of  the  ash-pit  doors. 
In  the  case  of  very  light  loads,  however,  it  is  best  to  use  both  the 
damper  and  the  ash-pit  doors  because  if  the  damper  alone  is 
used  there  may  be  a  positive  pressure  produced  in  the  upper 
part  of  the  setting,  causing  gas  and  smoke  to  leak  out  into  the 
fire  room. 

3.  Analyze  Flue  Gases  Frequently. — The  exact  position  of  the 
damper  to  suit  different  loads  can  only  be  determined  by  flue- 
gas  analysis.     The  CO2  should  be  kept  as  high  as  possible  without 
producing  CO.     If  it  is  found  impossible  to  secure  13J^  or  14 
per  cent,   of  C02  without  a  trace  of  CO,  then  there  is  something 
wrong  with  the  furnace  or  the  burners  and  an  investigation  should 


192  FUEL  OIL  AND  STEAM  ENGINEERING 

be  made.  The  proper  method  of  sampling  exit  gases  should  be 
used  as  it  is  quite  possible  through  improper  sampling  to  ob- 
tain very  poor  CO2  readings  even  though  the  furnace  may  be 
operating  quite  effectively.  If  correctly  measured,  the  greater 
the  CO2,  up  to  a  certain  limit,  the  greater  the  efficiency. 

4.  Burner  Must  Be  Suited  to  Furnace. — The  function   of  the 
oil  burner  is  to  atomize  the  oil,  and  the  most  efficient  burner  is 
the  burner  that  will  atomize  the  oil  with  the  least  quantity  of 
steam.     Burners  are  of  three  general  types — steam  jets,  mechani- 
cal-pressure jets  and  air  jets.     The  air  jet  is  largely  used  in  metal- 
lurgical work  while  the  mechanical  jet,  which  delivers  a  conical 
flame,  is  used  principally  in  marine  work  and  to  some  extent  in 
stationary  practice.     The  steam  atomization  burner  is  used   in 
stationary   and   locomotive   practice   almost    universally.     The 
choice  of  burners  for  central-station  furnaces  therefore  lies  be- 
tween the  steam  jet  and  the  mechanical,  the  shape  and  design  of 
the  furnace  influencing  the  type  selected. 

The  furnace  arrangement  is  the  most  important  part  of  the 
boiler  so  far  as  economy  of  operation  is  concerned.  If  the  air 
and  oil  are  not  properly  mixed,  it  will  be  impossible  to  obtain 
proper  combustion.  It  is  important  that  the  oil  be  completely 
burned  before  the  cooling  effect  of  the  heating  surfaces  can  oper- 
ate to  quench  the  fire.  A  large  combustion  chamber  is  of  great 
advantage  in  an  oil-burning  furnace,  as  the  larger  the  combustion 
chamber  the  more  complete  the  combustion  will  be  before  the 
gases  are  cooled. 

5.  Keep  Boilers  Clean  and  Maintain  Furnaces  Properly. — Oil 
burners  must  be  carefully  watched  as  they  are  liable  to  become 
clogged  with  foreign  matter  or  coated  with  carbon.     This  may 
cause  the  flame  to  shoot  sideways,  resulting  in  smoke  and  poor 
efficiency.     Therefore  a  spare  burner  should  always  be  kept  on 
hand,  so  that  as  soon  as  any  burner  gives  trouble  it  can  be  re- 
moved, taken  apart  and  cleaned.     All  burners  should  be  cleaned 
at  regular  intervals  and  adjusted  so  that  the  flame  will  not  be  pro- 
jected directly  against  the  boiler  tubes  or  against  the  boiler  set- 
ting, and  so  the  flames  from  different  burners  will  not  interfere 
with  one  another. 

The  checkerwork  in  the  furnace  floor  must  be  carefully  placed 
and  maintained  in  good  condition.  The  air  openings  often  be- 
come slagged  over  or  stopped  up  by  pieces  of  brick  breaking  off. 
Unless  they  are  cleaned  out  occasionally  and  kept  open  for  their 


EFFICIENT  OPERATION  OF  OIL  FIRED  BOILERS         193 


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194  FUEL  OIL  AND  STEAM  ENGINEERING 

full  area,  both  the  efficiency  and  capacity  of  the  boiler  will  be 
reduced. 

6.  Regulate  Atomizing  Steam  to  Suit  Oil. — The  regulation  of 
the  quantity  of  steam  used  for  atomizing  the  oil  is  a  matter  of 
very  great  importance,  for  if  more  steam  is  used  than  is  actually 
needed  there  is  not  only  a  waste  of  the  excess  quantity  of  steam 
but  there  is  also  a  loss  of  the  heat  required  to  raise  the  tempera- 
ture of  this  extra  steam  up  to  the  temperature  of  the  escaping 
gases.  With  careless  operation  the  quantity  of  steam  supplied 
to  the  burners  sometimes  amounts  to  as  much  as  5  per  cent,  of 
the  total  steam  generated  by  the  boiler,  whereas  with  proper 
care  in  operating  this  quantity  can  be  reduced  below  1  per  cent. 

A  simple  way  to  adjust  the  quantity  of  steam  supplied  is  to 
gradually  close  down  on  the  steam  valve  to  the  burner  until 
drops  of  oil  fall  on  the  furnace  floor.  The  drops  burn  and  scin- 
tillate and  can  be  readily  seen,  and  this  scintillation  indicates  that 
there  is  not  sufficient  steam  to  atomize  the  oil.  As  soon  as  this 
point  is  reached  the  steam  valve  should  be  opened  just  enough  to 
stop  the  scintillating  action. 

The  quantity  of  steam  supplied  to  the  burner  bears  an  im- 
portant relation  to  the  furnace  arrangement  and  the  air  supply, 
as  both  the  shape  and  character  of  the  flame  change  when  the 
quantity  of  steam  is  varied.  With  too  much  steam  an  intense 
white  flame  is  produced,  which  has  a  tendency  to  cause  localiza- 
tion of  heat  on  the  brickwork  or  the  tubes.  With  the  proper 
amount  of  steam  and  correct  air  regulation  a  soft  orange-colored 
flame  is  produced  which  fills  out  the  furnace  and  has  an  appear- 
ance similar  to  that  from  a  soft-coal  fire.  This  flame  will  some- 
times appear  smoky  in  the  furnace,  but  the  smoke  disappears 
before  the  gases  reach  the  stack.  It  is  therefore  unnecessary  to 
have  an  absolutely  clear  flame  in  the  furnace. 

A  simple  method  of  preventing  too  much  steam  being  used  for 
atomizing  where  boilers  are  operated  at  a  fairly  steady  load  is 
to  provide  a  disk  with  a  small  hole  in  it  in  the  steam  to  burner 
line.  This  disk  restricts  the  quantity  of  steam  that  can  pass 
through  the  burner.  The  size  of  the  hole  in  the  disk  depends  on 
the  steam  pressure  used  and  on  the  capacity  required  from  the 
boiler  and  must  be  determined  by  experiment.  In  a  plant  using 
200  Ib.  (14  kg.)  steam  pressure  a  hole  %e  m-  (7.9  mm.)  in  di- 
ameter has  been  found  large  enough  to  supply  all  the  atomizing 
steam  required  for  a  600-h.p.  boiler.  A  by-pass  should  be  pro- 


EFFICIENT  OPERATION  OF  OIL  FIRED  BOILERS        195 

vided  on  the  steam  line  so  as  to  pass  steam  around  the  disk  in 
case  it  is  found  necessary  to  force  the  boiler  at  any  time  above  its 
normal  capacity.  By  providing  the  by-pass  with  a  valve  hav- 
ing a  rising  stem  it  can  be  seen  at  a  glance  whether  the  valve  is 
open  or  shut. 

Superheated  steam  should  be  used  for  atomizing  wherever  it 
is  available,  as  the  higher  the  temperature  of  the  steam  the  more 
complete  the  atomization  will  be.  The  steam  to  the  burner 
should  always  be  cut  down  whenever  the  oil  is  cut  down.  Too 
often,  however,  the  firemen  leave  the  steam  flowing  full  blast 
even  after  the  oil  has  been  reduced  or  shut  off  altogether.  This 
is  an  absolutely  unnecessary  waste,  though  it  is  often  necessary 
to  keep  a  little  steam  flowing  through  a  burner  that  is  not  in 
use,  to  keep  it  cool  enough  to  prevent  damage  resulting  from 
the  heat  of  the  furnace. 

7.  Heat   Oil   to   Proper  Temperature  for  Atomization. — The 
quantity  of  steam  required  for  atomizing  depends  largely  on 
the  temperature  of  the  oil.     The  hotter  the  oil  the  less  steam 
is  required.     In  central  station  work  the  oil  should  be  heated  up 
to  about  180°F.  on  the  pressure  side  of  the  pumps,  the  pressure 
carried  running  from  40  to  60  Ib. 

Oil  should  never  be  heated  above  its  flash  point,  as  in  case  of  a  leak 
in  the  oil  pipe  there  will  be  danger  of  fire.  However,  atomization 
does  require  heating  the  oil  to  a  temperature  at  which  the  visco- 
sity is  sufficiently  lowered  to  make  the  oil  very  fluid.  Over  heat- 
ing of  an  oil,  due  to  its  expansion,  reduces  the  burner  capacity 
to  a  considerable  extent  and  also  introduces  the  element  of  risk. 

The  proper  temperature  of  the  oil  differs  for  different  oils. 
California  oils  require  heating  to  between  150°  and  180°F. 
(66°  and  82°C.).  The  higher  the  temperature  of  the  oil,  the  less 
steam  is  required  to  atomize  it. 

8.  Boilers  Should  not  be  Forced  Excessively. — Boilers  should 
never  be  forced  unless  necessary.     If  there  are  not  enough  boilers 
in  the  plant  to  maintain  steam  pressure  without  forcing  them, 
more  boilers  should  be  installed  or  the  steam  requirements  should 
be  reduced.     In  case  of  a  variable  load,  it  is  permissible  to  force 
the  boilers  for  short  periods  during  peak  load,  but  during  the 
periods  of  lighter  loads  the  same  number  of  boilers  should  be 
kept   in   operation   without  forcing.     Forcing  of  boilers  results 
in    high    flue-gas   temperature   and   should   not  be   resorted  to 
unless  the  plant  is  specially  designed  with  this  end  in  view  and 


196  FUEL  OIL  AND  STEAM  ENGINEERING 

provided  with  economizers  to  absorb  the  excess  temperature  of 
the  gases. 

9.  Shutting  Down  Boilers  for  Short  Periods  Should  be  Avoided. 
In  case  of   a  variable   load  it  is  more  economical  to  keep  the 
same  number  of  boilers  in  operation  continuously  than  to  fire  up 
extra  boilers  for  the  peak  load.     This  means  forcing  the  boilers 
somewhat  during  the  peak,  but  it  avoids  the  loss  due  to  heating 
up  cold  boiler  settings,  which  is  a  considerable  waste.     It  usually 
requires  eighteen  to  twenty  hours  to  heat  boiler  settings  to  their 
maximum  temperature,  so  it  is  desirable  to  keep  them  in  opera- 
tion as  steadily  as  practicable.     In  standby  plants  and  plants 
that  must  be  partly  or  wholly  shut  down  during  a  portion  of 
each  day  special  precautions  must  be  taken  to  prevent  waste  of 
oil  during  the  shut-down  period.     As  soon  as  the  oil  burners  are 
shut  off  the  ash-pit  doors  and  dampers  should  be  shut  tight.     If 
the  dampers  leak,  they  should  be  made  tight.     A  boiler  with  a 
tight  damper  will  maintain  its  full  steam  pressure  for  several 
hours  after  the  fires  are  put  out  if  no  steam  is  drawn  off.     If  the 
damper  leaks,  the  steam  pressure  will  begin  to  drop  immediately, 
and  much  more  oil  will  be  required  to  heat  up  the  boiler  when  it 
goes  back  into  service. 

10.  Oil  Should  not  be  Sprayed  into  Furnace  Unless  There  is  a 
Fire. — In  operating  oil-fired  boilers  it  is  extremely  important  to 
avoid  any  accumulation  of  gas  in  the  boiler  setting  because  of  the 
danger  of  explosion;  consequently  no  oil  should  be  allowed  to  get 
into  the  furnace  unless  there  is  a  fire  to  ignite  it  and  no  more  oil 
should  be  fed  into  the  furnace  than  can  be  burned  with  the  avail- 
able quantity  of  air  and  atomizing  steam. 

To  light  an  oil  fire  under  a  boiler,  first  open  the  damper  and 
ash-pit  doors;  next  place  a  lighted  torch  in  front  of  the  burner; 
next  turn  on  the  atomizing  steam;  next  turn  on  the  oil,  which 
should  immediately  ignite.  If  the  oil  does  not  ignite  immediately, 
turn  it  off  at  once  and  investigate  to  find  out  the  reason  be- 
fore turning  it  on  again. 

11.  Feed  Water  Uniformly. — Water  should  be  fed  to  the  boilers 
continuously  and  uniformly.     If  it  is  fed  intermittently  it  may 
become  too  hot  in  the  feed-water  heater  to  absorb  all  of  the  heat 
in  the  exhaust  steam,  and  at  other  times  it  will  be  too  cold,  thus 
causing  considerable  waste.     Intermittent  feeding  also    results 
in  unsteady  steam  pressure,  which  in  turn  means  frequent  altering 
of  the  fires,  variable  furnace  temperature  and  increased  difficulty 


EFFICIENT  OPERATION  OF  OIL  FIRED  BOILERS        197 


198  FUEL  OIL  AND  STEAM  ENGINEERING 

in  regulating  the  air  supply.  For  best  efficiency  the  furnace 
conditions  should  be  kept  as  steady  as  possible.  It  is  better  to 
allow  the  steam  pressure  to  vary  a  few  pounds  than  to  be 
continually  altering  the  fires. 

12.  Keep  Boilers  Clean  and  in  Good  Repair. — The  importance 
of  keeping  the  boiler  clean  both  inside  and  outside  and  in  good 
repair  is  recognized  by  every  operating  engineer  and  need  not  be 
enlarged  upon  here.    There  are  some  engineers,  however,  who, 
while  realizing  that  the  boilers  must  be  kept  clean,  are  of  the 
opinion  that  the  quantity  of  soot  resulting  from  an  oil  fire  is  so 
slight  as  to  be  negligible.     Experience  shows,  however,  that  this 
is  not  the  case,  and  it  is  essential  to  provide  either  mechanical 
soot  blowers  or  some  sort  of  steam  lance  with  all  oil-burning 
boilers.    Furthermore,    it    is    essential  that  these   devices    be 
used  at  intervals  frequent  enough  to  keep  the  heating  surface  of 
the  boiler  free  from  deposits  of  soot.     In  actual  practice  it  is 
found  that  blowing  the  soot  from  the  tubes  of  an  oil-fired  boiler 
results  in  a  reduction  in  flue-gas  temperature  of  80°  to  100°F.(45° 
to  55°C.),  which  means  an  increase  in  efficiency  of  1%  to  3  per 
cent. 

The  inside  of  the  boiler  must  be  thoroughly  washed  out  and  all 
scale  removed  at  regular  intervals,  the  length  of  interval  depend- 
ing on  the  quality  of  feed  water  used.  Scale  should  not  be 
allowed  to  accumulate  more  than  J£  in.  (3.2  mm.)  thick.  The 
soot  on  the  outside  of  the  boiler  should  be  blown  off  at  least  once 
a  day.  Scale  and  soot  constitute  extremely  efficient  heat  insu- 
lation materials,  the  thermal  conductivity  of  scale  being  about 
one-fifth  that  of  steel  so  that  %  in.  (6.4  mm.)  of  scale  is  equi- 
valent to  a  boiler  tube  1%  in.  (3.2  cm.)  thick. 

The  boilers  should  be  blown  down  regularly  at  least  once  a 
day,  and  oftener  if  the  water  contains  soluble  salts  which  tend  to 
cause  foaming.  About  half  a  gage  glass  of  water  should  be 
blown  out  each  time,  and  this  should  preferably  be  done  when 
there  is  no  fire  under  the  boiler.  Samples  of  water  drawn  from 
the  boiler  should  be  tested  for  salt,  which  should  not  be  allowed 
to  concentrate  above  150  grains  per  gallon  (2.53  gm.  per  cu.  dcm.). 

13.  Maintain  Baffles  and  Flame  Plates  in  Good   Condition. — 
If  boiler  baffles  are  allowed  to  become  displaced,  the  gases  will 
short-circuit  from  one  pass  to  another,   making  some   portions 
of  the  heating  surface  ineffective.     This  results  in  high   stack 
temperature  and  poor  economy.     The  baffles  should  be  kept  gas- 


EFFICIENT  OPERATION  OF  OIL  FIRED  BOILERS        199 


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200  FUEL  OIL  AND  STEAM  ENGINEERING 

tight  at  all  times,  and  any  baffle  tiles  that  have  been  disturbed 
by  the  replacing  of  tubes,  gas  explosions  or  from  any  other  cause 
should  be  put  back  into  proper  condition  before  the  boiler  is 
fired  up.  The  openings  through  the  baffles  for  the  passage  of 
gases  should  be  maintained  the  right  area  to  suit  the  capacity 
required  and  the  draft  available. 

14.  Use     Recording    Instruments    Wherever    Practicable. — 
Reliable  records  of  the  actual  performances  of  a  plant  are  of  great 
aid  to  its  efficient  operation.     By  this  means  guess  work  is 
avoided  and  it  can  be  determined  accurately  what  method  of 
operation  or  which  man  produces  the  greatest  efficiency.     To 
obtain  efficient  results  means  not  only  the  installation  of  efficient 
machinery  and  recording  apparatus  but  constant  attention  to 
operation. 

Recording  CO2  meters  or  an  Orsat  apparatus  and  draft  gages 
are  essential  for  efficient  furnace  operation,  because  they  show 
excess  air  entering  the  furnace — the  greatest  single  avoidable 
loss  in  the  combustion  of  fuel.  Recording  steam  gages  and  flow 
meters  are  also  of  considerable  assistance,  the  latter  particularly 
because  they  show  the  quantity  of  steam  generated  by  each 
boiler.  A  pyrometer  or  flue-gas  thermometer  should  be  used  to 
measure  the  temperature  of  the  exit  gases.  An  additional 
steam-flow  meter  should  be  connected  to  the  atomizing  steam 
pipe  and  a  record  kept  of  the  quantity  of  steam  used  by  the 
burners.  Thermometers  and  recording  pressure  gages  on  the 
steam  and  oil  lines  close  to  the  burners  also  give  valuable 
information. 

15.  Determine  Efficiency  Daily  from  Records. — The    actual 
evaporation  per  pound  of  oil  may  be  obtained  by  means  of  water 
meters  and  oil  meters.     The  quantity  of  steam  used  by  the 
burners  may  be  obtained  by  means  of  a  steam-flow  meter  in  the 
steam-to-burner   line.     The    greater   the   net    evaporation    per 
pound  of  oil,  the  higher  is  the  efficiency  of  the  boiler. 

By  keeping  accurate  records  of  the  daily  performances  of 
boilers  it  is  possible  to  compare  one  day's  results  with  another. 
By  trying  different  methods  of  operation,  different  furnace 
arrangements  and  different  intensities  of  draft  and  comparing 
one  with  another,  the  best  and  most  economical  method  of 
operating  may  be  determined  with  certainty. 

16.  Fire  Boilers  Scientifically. — Boilers  should  be  fired  scien- 
tifically ;  that  is,  by  basing  the  method  of  operation  on  the  flue- 


EFFICIENT  OPERATION  OF  OIL  FIRED  BOILERS       201 

gas  analysis,  temperature  of  escaping  gases  and  results  of  tests 
and  plant  records.  With  careful  attention  paid  to  the  draft 
readings  and  adjustments  of  dampers,  this  method  will  usually 
result  in  considerable  saving.  The  recognition  that  trained 
engineers  are  rapidly  receiving  is  most  convincing  testimony 
that  the  value  of  scientific  management  is  becoming  increasingly 
appreciated. 


FIG.  122. — Five  outlets  for  measuring  chimney  draft  pressures  with  one  draft 

nrti  nro 


gage 

Co-operation  with  the  employer  and  with  other  employees  is 
absolutely  necessary  for  successful  operation  of  the  plant.  If 
the  plant  requires  new  equipment  or  repairs  to  old  equipment 
in  order  to  improve  its  economy,  these  improvements  should 
be  suggested  to  the  employer,  with  an  explanation  of  the  resulting 
advantages. 


CHAPTER  XXIV 
FUEL  OIL  BURNING  APPLIANCES 

In  its  course  from  the  point  of  delivery  at  the  plant  to  the 
burners  the  oil  must  pass  through  a  number  of  appliances,  which 
are  necessary  for  the  complete  equipment  of  any  oil  burning 
plant.  In  this  discussion  we  shall  follow  the  oil  in  its  journey 
through  the  plant  and  describe  briefly  the  various  appliances 
required  for  handling  it. 


FIG.  123. — The  cars  are  shown  on  the  unloading  track  of  the  Redondo  Steam 
Plant  of  the  Southern  California  Edison  Company  and  the  oil  is  emptied  from 
them  into  the  flume  which  runs  beside  the  tank;  thence  it  goes  into  a  small 
underground  tank  from  which  it  is  pumped  into  the  main  storage  tank. 

Oil  may  be  delivered  at  the  plant  either  by  rail  in  tank  cars, 
or  by  water  in  barges  or  tank  steamers  specially  constructed  for 
the  purpose.  From  these  it  is  pumped  into  large  storage  tanks, 
which  may  be  of  either  concrete  or  steel. 

Storage  Tanks. — For  power  plants  large  cylindrical  steel 
storage  tanks  are  used,  These  are  usually  set  on  the  ground 

202 


FUEL  OIL  BURNING  APPLIANCES  203 

outside  the  plant,  and  are  built  in  any  desired  size  up  to  50,000 
bbl.  capacity.  They  are  built  up  of  riveted  steel  plates,  the 
thickness  of  plate  and  strength  of  riveted  joint  being  propor- 
tioned in  accordance  with  the  usual  safety  rules  based  on  the 
internal  pressure  due  to  the  head  of  oil  inside  the  tank.  Thus 
if  the  tank  is  30  ft.  high  the  internal  pressure  will  be  that  due  to 
30  ft.  head  of  oil,  or  approximately  15  Ib.  per  square  inch.  It 
is  customary  to  surround  the  storage  tank  by  a  concrete  wall 
about  10  ft.  high  far  enough  away  from  the  tank  so  that  the  entire 


FIG.  124. — Main  oil  storage  tanks  at  Station  C,  Pacific  Gas  and  Electric 
Company,  Oakland,  California.  Tank  in  foreground  is  set  low  for  fire  pro- 
tection purposes,  while  tank  in  rear  is  surrounded  by  concrete  retaining  walls. 

contents  of  the  tank  will  be  held  in  by  the  wall  in  case  of  a  leak 
in  the  tank.  This  is  to  prevent  the  oil  from  leaking  out  to  the 
surrounding  country. 

The  size  of  storage  tank  required  depends  on  two  factors: 

1.  Quantity  of  oil  to  be  burned. 

2.  Availability  of  oil  supply. 

This  second  factor  depends  on  the  location  of  plant,  the  method 
of  delivery,  and  the  probability  of  interruptions  in  delivery,  all  of 
which  matters  must  be  carefully  considered  in  determining  the 
number  of  days  oil  supply  that  should  be  carried  at  the  plant. 
Most  power  plants  are  provided  with  tanks  of  sufficient  size  to 
enable  them  to  keep  from  10  to  30  days'  supply  of  oil  on  hand. 


204  FUEL  OIL  AND  STEAM  ENGINEERING 

This  storage  capacity  should  preferably  be  divided  among  two 
or  more  tanks  rather  than  all  concentrated  in  a  single  tank,  as 
this  will  enable  one  tank  to  be  emptied  for  cleaning  and  repairs 
without  shutting  down  the  entire  plant. 

In  built  up  districts  within  the  fire  limits  of  cities  it  is  not 
permissible  to  locate  the  storage  tanks  above  ground.  The 
National  Board  of  Fire  Underwriters  have  adopted  certain 
rules  for  the  location  of  oil  storage  tanks,  which  will  be  found  in 


FIG.  125. — One  of  the  pumps  which  handle  the  oil  from  the  main  storage 
tank  to  the  auxiliary  tank.  This  pump  was  originally  arranged  for  belt  drive 
but  was  found  unsatisfactory.  The  gearing  is  now  direct. 

Appendix  III,  page  415.  Similar  rules  have  been  adopted  by 
several  cities.  In  general  these  rules  provide  that  within  the 
fire  limits  of  cities  the  tank  must  be  located  so  that  its  top  is  at 
least  3  ft.  below  the  level  of  the  fireroom  floor  and  below  the 
lowest  pipe  in  the  building  to  be  supplied.  The  tank  must  be 
set  on  a  firm  foundation  and  covered  with  soft  earth  or  sand, 
no  air  ^pace  being;  allowed  immediately  outside  the  tank. 


FUEL  OIL  BURNING  APPLIANCES  205 

Eveiy  oil  storage  tank  must  be  provided  with  the  following 
attachments : 

Filling  pipe 
Suction  pipe 
Vent  pipe 
Smothering  pipe 
Overflow  pipe 
Measuring  rod  or  chain 


For  tanks  less  than  1000  gal.  capacity  the  filling  pipe  and 
vent  pipe  may  be  on  the  same  connection.  For  larger  tanks 
separate  connections  are  required.  The  vent  pipe  must  extend 
from  the  top  of  the  tank  to  a  point  outside  the  building  at  least 
12  ft.  above  the  top  of  the  highest  tank  car  from  which  the  storage 
tank  may  be  filled.  All  outlets  on  the  tank  should  be  located  on 
top,  the  suction  pipe  running  down  inside  the  tank  to  near  the 
bottom.  The  smothering  pipe  consists  of  a  small  steam  pipe 
through  which  steam  can  be  blown  in  case  of  fire,  thus  keeping 
air  away  and  effectually  smothering  the  flames.  The  overflow 
pipe  is  arranged  to  carry  back  to  the  storage  tank  all  oil  not  used. 
An  automatic  relief  valve  is  provided  on  the  oil  pump  discharge 
set  to  open  at  a  predetermined  pressure,  and  discharging  through 
the  overflow  pipe  back  to  the  storage  tank.  All  pipes  should  be 
run  as  direct  as  possible  and  pitched  toward  the  storage  tank. 
The  oil  in  the  tank  may  be  measured  by  means  of  a  rod  or  chain 
let  down  through  the  top  of  the  tank.  The  use  of  gage  glasses 
should  be  avoided  as  they  are  liable  to  break,  causing  leakage  of 
oil. 

Many  power  plants  are  provided  with  a  service  tank 
located  under  the  fireroom  floor,  in  addition  to  the  main 
storage  tank  outside  the  building.  The  service  tank  is  filled 
at  intervals  from  the  storage  tank,  and  the  oil  pumps  take 
their  supply  from  the  service  tank  and  distribute  it  to  the  oil 
burners. 

Measurement  of  Oil. — Oil  is  ordinarily  measured  by  passing  a 
rod  or  chain  down  through  the  top  of  the  storage  tank,  the  rod 
being  marked  off  in  feet,  inches  and  fractions  of  an  inch.  By 
sounding  to  the  bottom  of  the  tank,  the  depth  of  oil  can  be 
determined  very  accurately.  A  more  convenient  method, 
though  not  quite  so  accurate,  is  to  use  a  float  with  a  chain  passing 
over  a  pulley  at  the  top  of  the  tank,  the  outer  end  having  a 


206 


FUEL  OIL  AND  STEAM  ENGINEERING 


pointer  which  indicates  the  height  of  oil  in  the  tank  on  a  suitably 
calibrated  scale.  The  height  of  oil  in  the  tank  may  also  be 
determined  by  an  indicating  or  recording  pressure  gage,  which 
depends  for  its  operation  on  the  hydrostatic  pressure  produced  by 
the  oil. 

After  determining  the  height  of  oil  in  the  tank  it  is  necessary 
to  convert  the  measurement  into  gallons  or  barrels  of  oil.  To  do 
this  it  is  necessary  to  carefully  calibrate  the  tank  either  by  pump- 

ing  into  it  known  quantities  of  oil, 

or  by  taking  careful  measurements 
and  calculating  its  contents.  This 
latter  method  is  very  simple  if  the 
tank  has  vertical  sides.  If,  how- 
ever, a  cylindrical  tank  lying  hori- 
zontally is  used,  the  calculation  is 
somewhat  complicated.  The  table  in 
Fig.  127  giving  the  capacity  of  hori- 
zontal cylindrical  tanks  per  foot  of 
length  for  various  depths  of  liquid 
will  be  of  assistance  in  this  connection. 
After  determining  the  volume  of  oil 
in  a  tank  it  is  necessary  to  make 
correction  for  its  temperature,  for, 
like  everything  else,  oil  expands  and 
contracts  with  changes  of  temperature 
and  the  volume  measured  at  one 
temperature  will  not  be  the  same  as 
the  volume  of  the  same  weight  of  oil 
at  another  temperature.  The  amount 
of  variation  of  the  volume  of  the  oil 
depends  on  its  coefficient  of  expansion. 
The  coefficient  of  expansion  varies  for 
different  oils,  but  the  average  value 
for  California  oils  is  usually  taken  at 
0.0004  for  each  degree  Fahrenheit 
change  in  temperature;  that  is,  the 
oil  expands  four  ten  thousandths  of 

its  volume  for  each  degree  F.  rise  in  temperature.  This  is  equiva- 
lent to  0.00072  per  degree  Centigrade. 

In  practice  60°F.  has  been  adopted  as  the  standard  tempera- 


FIG.  126. — Gage  to  measure 
height  of  oil  in  30,000  barrel 
tank  at  North  Beach  Steam 
Plant  of  Sierra  and  San  Fran- 
cisco Power  Company,  San 
Francisco.  The  rod  inside  the 
pipe  is  calibrated  in  feet  and 
inches,  passes  down  into  the 
tank  and  rests  on  a  float  sup- 
ported by  the  oil.  An  electric 
lamp  attached  to  counter 
weight  enables  it  to  be  seen  at 
night. 


FUEL  OIL  BURNING  APPLIANCES 


207 


FIG.  127. — Tabulated  data  on  cylinder  volumes. 


FIG.  128.— Fuel  oil  pumps  and  heaters,  PaciHc  Gas  and  Electric  Company 


station 
pumps. 


C,   Oakland.    "Below  are  shown  the  duplicate  reciprocating  fuel 
Above  is  a  large  air  receiver  and  a  coil  pipe  oil  heater. 


oil 


208 


FUEL  OIL  AND  STEAM  ENGINEERING 


ture,  and  to  reduce  the  measured  volume  to  the  true  volume  at 
60°F.  the  following  formula  is  used: 

V 


[(*-  60)  x  0.0004)] 
where  F6o  =  the  volume  of  oil  at  60°F. 

Vt  =  the  volume  of  oil  as  measured,  both  expressed  in 

barrels,  gallons  or  cubic  feet  as  the  case  may  be. 
t  =  temperature  of  the  oil  when  measured,  in  degrees  F. 


FIG.  129. — One  unit  of  a  duplicate  set  in  the  Long  Beach  Steam  Plant  of  the 
Southern  California  Edison  Company,  consisting  of  a  fuel  oil  pump  in  the  fore- 
ground \yith  the  oil  heater  immediately  behind  it. 

Thus  if  the  sounding  in  a  tank  before  and  after  rilling  show,  that 
960  bbl.  have  been  added,  and  the  observed  temperature  of  the 
oil  was  80°F.,  then  the  true  volume  at  60°F. 


F60  = 


960 


1  +  (20  X  0.0004) 


=  952  bbl. 


FUEL  OIL  BURNING  APPLIANCES 


209 


If  instead  of  80°F.  the  temperature  of  the  oil  had  been  50°F.,  the 
true  volume  at  60°F.  would  be 


F60   =  - 


960 


=  964  bbl. 


-10  X  0.0004] 

Oil  Pumps.— The  oil  is  taken  from  the  supply  tank  by  the  oil 
pump.  The  type  of  pump  usually  used  for  this  purpose  is  the 
ordinary  duplex  steam  driven  reciprocating  pump.  The  pump 


FIG.   130. — The  Witt  pump  governor.     It  controls  the  running  of  a  pump  and 
will  hold  a  steady  pressure  on  the  discharge  line. 

must  have  brass  valves,  and  metallic  or  other  packing  that 
will  not  be  affected  by  the  oil.  The  pump  should  be  provided 
with  a  large  air  chamber  to  prevent  pulsations  of  oil  pressure  due 
to  the  strokes  of  the  pump.  It  is  customary  to  install  the  pumps 
in  duplicate  so  that  one  may  be  kept  shut  down  at  all  times  ready 
to  go  into  service  immediately  if  the  other  has  to  be  shut  down  for 
repairs.  The  pumps  should  be  of  sufficient  size  to  deliver  the 
maximum  quantity  of  oil  required  when  operating  at  compara- 

14 


210 


FUEL  OIL  AND  STEAM  ENGINEERING 


lively  slow  speed — not  more  than  15-20  strokes  per  minute. 
The  pump  must  not  be  set  too  high  above  the  oil  tank,  for  oil 
cannot  be  raised  by  suction  as  high  as  water.  The  maximum 
suction  lift  permissible  is  about  16  ft. 

The  oil  pumps  should  be  provided  with  a  pump  governor  for 
the  purpose  of  maintaining  a  steady  oil  pressure.  An  example 
of  this  is  the  Witt  pump  governor  shown  on  page  209.  It 
consists  of  a  double  ported  throttle  valve  placed  on  the  steam 


FIG.  131. — Fuel  oil  pumps  for  turbine  No.  3  at  the  Long  Beach  Plant  of  the 
Southern  California  Edison  Company.  Note  the  neat  and  attractive  appear- 
ance throughout  in  this  interesting  installation,  quite  typical  where  oil  is  used 
as  fuel. 

line  supplying  the  pump.  The  valve  stem  is  attached  to  a 
spring  loaded  piston  which  is  actuated  by  the  oil  pressure.  If 
the  oil  pressure  increases  the  valve  partially  closes,  thus  slowing 
down  the  pump.  If  the  oil  pressure  drops  the  valve  opens  wider 
and  the  pump  is  speeded  up.  Any  predetermined  pressure  may 
thus  be  maintained  by  adjusting  the  spring. 

Strainers. — Every  oil  burning  plant  must  be  provided  with 
some  form  of  strainer  to  remove  the  dirt  and  foreign  matter 
which  would  be  liable  to  cause  stoppage  of  the  burners.  The 
strainer  may  be  placed  either  in  the  suction  line  between  the 
supply  tank  and  the  pump,  or  in  the  discharge  line  after  leaving 


FUEL  OIL  BURNING  APPLIANCES 


211 


the  pump,  or  both.  The  strainer  usually  consists  of  a  perforated 
metal  basket  mounted  in  a  suitable  container,  arranged  so  that 
the  basket  can  be  readily  removed  for  cleaning.  The  Staples 


FIG.   132. — Staples  and  Pfeiffer  self-cleaning  oil  strainer. 

and  Pfeiffer  so-called  self -cleaning  strainer,  which  is  shown  in  the 
illustration,  is  provided  with  a  by-pass  and  arranged  so  that 
the  dirt  can  be  blown  out  by  a  steam  jet  without  removing  the 
basket. 


FIG.  133. — This  is  a  simple  form  of 
a  strainer  in  which  the  basket  can  be 
readily  removed  for  cleaning. 


FIG.   134. — The  Elliott  twin  oil 
strainer. 


In  addition  to  the  main  strainer  on  the  oil  line  it  is  advisable 
to  provide  a  small  fine  mesh  strainer  at  each  oil  burner.  To  clean 
this  strainer  it  is  only  necessary  to  turn  the  handle  on  top  so  as 
to  run  the  oil  through  the  by-pass,  place  a  bucket  under  the 


212 


FUEL  OIL  AND  STEAM  ENGINEERING 


blowout  valve  at  the  bottom  and  blow  steam  through  by  opening 
the  small  valve  on  the  side. 

Oil  Heaters. — Before  reaching  the  oil  burners  the  oil  must  be 
passed  through  an  oil  heater  to  bring  it  up  to  a  temperature 
suitable  for  atomizing.  The  oil  heater  is  usually  placed  between 
the  pump  and  the  oil  burners,  a  convenient  method  being  to 
mount  the  pumps  over  the  heater,  as  shown  in  Fig.  135  the  ex- 
haust steam  from  the  pump  being  utilized  as  the  heating  medium. 


FIG.  135. — Staples  and   Pfeiffer  oil  pump   and   heater  unit. 


1.  Steam  to  pumps 

2.  Pump        governor      and 

pressure  regulator 

3.  Steam  by-pass  valve 

4.  Steam  valves 

5.  Exhaust  steam  valves 

G.  Pop  safety  valve  in  ex- 
haust, line 

7.  Exhaust  steam  in  heater 

8.  Pop     safety     valve     for 

heater 

9.  Exhaust     from     coil    to 

trap  or  atmosphere 


10.  Heater     oil     drain     and 

blow-out 

11.  Side  feed  lubricator 

12.  Duplex  pumps 

13.  Independent    exhaust 

cone 

14.  Drip  pan 

15.  Heater  head 

16.  Oil  heater 

17.  Copper  coil 

18.  Air  cushion  tank 

19.  Automatic  relief  valve 

20.  Oil  return  to  tank 


21.  Oil  discharge  valve 

22.  Gas  relief  valves 

23.  Oil  suction  valves 

24.  Suction  oil  strainer 

25.  Steam  blow-out  valves 

26.  Strainer  blow-out  valves 

27.  Oil  suction  from  tank 

28.  Oil  discharge  to  burner 

29.  Oil  discharge  strainer 

30.  Cold  oil  by-pass  valve 


Heaters  invariably  consist  of  a  series  of  tubes  or  coils  with 
oil  on  one  side  of  the  metal  and  steam  on  the  other,  the  heat 
passing  through  the  metal  from  the  steam  to  the  oil.  There  are 
several  different  ways  in  which  this  may  be  accomplished :  thus 
the  heating  surface  may  be  composed  of  either  a  coil  or  a  number 
of  straight  tubes;  the  oil  may  flow  through  the  tubes  with  the 
steam  outside,  or  the  oil  may  surround  the  tubes  with  the  steam 


FUEL  OIL  BURNING  APPLIANCES  213 

on  the  inside.     All  of  these  methods  are  used  in  different  heaters 
now  on  the  market. 

The  size  of  heater  is  determined  by  the  formula 

S  =  Hk  (ts  -  to) 

where  8  =  heating  surface  in  square  feet. 

H  =  heat  absorbed  in  B.t.u.  per  hour. 
k  =  coefficient  of  heat  transfer. 

=  B.t.u.  absorbed  per  hour  per  square  foot  per  degree 

difference  in  temperature. 
ta  —  mean  temperature  of  steam,  deg.  F. 
to  =  mean  temperature  of  oil,  deg.  F. 


FIG.  136. — Nelson  Fuel  Oil  Heater.  This  is  a  multipass  heater  using  the 
principle  of  "porcupine"  tubes,  the  tubes  being  free  at  one  end  for  expansion 
and  contraction. 

The  quantity  H,  heat  absorbed  per  hour,  is  found  readily  by  the 
formula 

H  =  W  fe  -  «i)c 

where  W  =  weight  of  oil  heated  per  hour  in  pounds. 
ti  =  initial  temperature  of  oil,  degrees  F. 
tz  =  final  temperature  of  oil,  degrees  F. 
c  =  specific  heat  of  oil  =  0.498. 

The  quantity  /c,  coefficient  of  heat  transfer  varies  with  the  differ- 
ence in  temperature  between  the  steam  and  the  oil,  and  with  the 
velocity  of  oil  in  passing  through  or  around  the  tubes.  This 
velocity  is  of  great  importance,  as  the  greater  the  velocity  the 
better  is  the  oil  scraped  from  the  side  of  the  tube,  thus  allowing 
colder  oil  to  come  in  contact  with  the  hot  surface.  It  is  evident 


214 


FUEL  OIL  AND  STEAM  ENGINEERING 


therefore  that  a  high  velocity  of  oil  is  desirable.     There  is  a 
limit,  however,  to  the  velocity  attainable,   as  the  higher  the 


FIG.  137. — The  "  Coeu  "  multiunit  oil  heater. 

velocity  the  greater  is  the  drop  in  pressure  of  the  oil  in  passing 
through  the  heater.  The  drop  in  pressure  in  turn  depends  largely 
on  the  viscosity  of  the  oil,  so  that  viscosity  has  an  important 
bearing  on  the  heat  transfer.  The  value  of 
the  coefficient,  k,  therefore  varies  between 
wide  limits  and  for  ordinary  conditions  may 
be  said  to  lie  between  15  and  50  B.t.u.  per 
hour  per  square  foot  per  degree  difference  in 
temperature. 

For  a  heater  in  which  the  oil  flows  through 
the  tubes  it  is  a  simple  matter  to  divide  the 
flow  into  passes  so  as  to  obtain  the  required 
velocity,  the  oil  passing  through  first  one  group 
of  tubes  and  then  another.  If  the  heater  is 
designed  to  contain  the  oil  in  a  shell  outside 
the  tubes,  there  is  a  tendency  for  the  oil  to 
short  circuit  across  from  the  inlet  to  the  out- 
let, leaving  portions  of  the  heating  surface 
surrounded  by  dead  or  stagnant  oil.  To 
overcome  this  it  is  necessary  to  place  baffles 
in  the  shell  causing  the  oil  to  travel  back  and 
forth,  and  producing  what  is  known  as  tur- 
bulent flow.  If  the  baffles  are  properly 
designed  and  the  oil  flow  is  sufficiently 
agitated  it  is  possible  to  obtain  as  good 
heat  transfer  for  a  given  drop  in  pressure  by 
this  means  as  by  passing  the  oil  through  the 
tubes. 

While  oil  heaters  usually  consist  of  a  shell  containing  a  series 
of  tubes  or  coils,  there  are  on  the  market  a  few  special  designs. 


FIG.  13  8.— T  h  e 
Koerting  fuel  oil 
heater. 


FUEL  OIL  BURNING  APPLIANCES 


215 


One  of  these  is  the  Coen  multiunit  oil  heater,  which  is  illustrated 
in  Fig.  137.  This  heater  is  similar  in  design  to  the  ordinary 
ammonia  condenser  used  in  ice  machines,  and  consists  of  a  series 
of  double  pipes,  one  inside  the  other,  connected  together  by 
standard  ammonia  fittings.  This  heater  may  be  constructed  in 
any  length  or  number  of  legs  as  desired.  The  oil  passes  through 
the  inside  pipe,  and  the  steam  is  in  the  annular  space  between  the 
two  pipes. 

Another  heater  of  unusual  design  is  the  Koerting  Fuel  Oil 
Heater,  illustrated  in  Fig.  138.  This  heater  consists  of  a 
pair  of  spiral  corrugated  tubes, 
one  inside  the  other,  and  both  in- 
closed in  a  shell.  The  oil  enters  at 
EO  and  passes  up  the  thin  annular 
space,  leaving  at  DO.  The  steam 
enters  at  ES,  and  is  carried  both 
inside  the  inner  tube  and  outside 
the  outer  tube.  For  cleaning,  the 
inner  tube  may  be  removed,  or 
steam  blown  through  the  plugged 
openings  FF. 

Oil  Burners. — After  leaving  the 
heater  the  oil  is  led  through  piping 
and  suitable  regulating  valves  to 
the  oil  burners  or  atomizers,  where 
it  comes  in  contact  with  the  atomiz- 
ing agent  and  is  delivered  to  the 
furnace  in  the  form  of  a  fine  spray. 
A  description  of  a  number  of  dif- 
ferent types  of  oil  burners  will  be 
found  in  Chapters  XXI  and  XXII. 

Oil  Piping. — Ordinary  wrought 
iron  or  steel  pipe  is  used  for  oil, 
the  smaller  sizes  being  screwed  and 

, ,      ,  n  ,        ~      ,  f  FIG.   139.— G.  E.  Witt  Co.'s  im- 

the  larger  flanged.     Gaskets  of  cor-  proved  oil  burner  governor.     A 

rugated       copper       Or       compressed    device  for  automatically  controlling 

the  flow  of  steam  and  oil  to  burners. 

asbestos  fibre  are  used.     The  size 

of  pipe  in  most  power  plants  is  such  as  to  give  the  oil  a  velocity 

of  not  more  than  2  ft.  per  second. 

Automatic  Regulators. — While  in  the  majority  of  plants  the 
oil  is  regulated  by  means  of  hand  operated  valves,  automatic 


216 


FUEL  OIL  AND  STEAM  ENGINEERING 


regulation    has    met    with    great    success    and    is    used    quite 
extensively. 

The  Witt  improved  oil  burner  governor  shown  in  the  illustration 
on  page  215  consists  of  two  independent  diaphragm  operated 
valves,  controlled  by  springs,  mounted  so  as  to  have  the  boiler 
steam  pressure  between  the  two  diaphragms.  This  governor  regu- 
lates both  the  oil  supply  and  the  steam  supply  to  the  burners. 


FIG.  140. — On  the  left  may  be  observed  oil-to-burner  Moore  regulator  control- 
ling the  steam  pressure  and  the  oil  pressure  while  on  the  right  may  be  seen  the 
damper  controller  that  works  by  hydraulic  cylinder  actuation  at  the  Arizona 
Power  Company,  Phoenix,  Arizona. 

It  is  provided  with  pilot  valves  which  prevent  the  fire  going  out 
when  the  load  is  light,  and  with  maximum  valves  which  prevent 
the  fires  becoming  larger  than  a  predetermined  point.  The 
governor,  therefore,  regulates  the  oil  and  steam  between  these 
two  extremes. 

The  Moore  automatic  fuel  oilregulator,  which  is  illustrated  in  Figs. 
9,  140,  141  and  142  regulates  not  only  the  oil  and  steam  but  also 


FUEL  OIL  BURNING  APPLIANCES  217 

the  air  required  for  combustion,  thus  controlling  the  three  es- 
sential elements  for  firing  the  boiler.  This  apparatus  consists 
of  three  separate  regulators,  one  for  the  oil,  one  for  the  atomizing 
steam  and  one  for  the  air.  These  regulators  are  made  up  on  the 
principle  of  the  well  known  Spencer  damper  regulator,  and  the 
set  of  three  can  be  arranged  by  suitable  piping  and  shafting  to 
control  the  firing  of  a  number  of  boilers,  and  in  many  cases  of  the 
whole  plant.  In  the  oil  regulator  the  diaphragm  is  operated  by 


FIG.  141. — Moore  steam  to  burner  regulator  controlling  the  atomizing  steam  at 
the  Arizona  Power  Company's  Plant,  Phoenix,  Arizona. 

the  boiler  steam  pressure,  and  the  power  lever  is  used  to  control 
a  regulating  valve  in  the  main  oil  pipe  supplying  the  burners. 
By  this  means  a  slight  change  in  the  boiler  pressure  is  made 
to  cause  considerable  change  in  the  oil  pressure,  and  as  the 
quantity  of  oil  supplied  to  the  burners  varies  with  the  oil  pres- 
sure, the  fires  in  all  boilers  are  increased  or  diminished  gradually 
and  simultaneously.  This  variable  oil  pressure  is  then  made  to 
act  on  the  diaphragms  of  the  other  two  regulators. 

In  the  atomizing  steam  regulator  there  are  two  diaphragms, 
one  acted  on  by  the  controlling  oil  pressure  and  the  other  con- 


218  FUEL  OIL  AND  STEAM  ENGINEERING 

nected  to  the  atomizing  steam  pressure  near  the  burners.  These 
diaphragms  are  connected  by  levers  which,  acting  through  the 
water  motor  and  connecting  rod  operate  a  chronometer  valve  in 
the  atomizing  steam  main.  Thus  any  increase  in  oil  pressure 
causes  a  definite  fixed  increase  in  atomizing  steam  pressure.  The 
steam  pressure  required  has  been  found  by  experiment  to  be  a 
multiple  of  the  oil  pressure  plus  a  fixed  pressure.  This  relation- 


FIG.  142. — Damper  regulator  for  Moore  automatic  oil  firing  system  at  the  Ari- 
zona Power  Company's  Plant,  Phoenix,  Arizona. 

ship  is  maintained  by  the  regulator,  the  proportion  being  varied 
by  the  adjustable  fulcrum  and  weights  to  suit  the  requirements 
of  the  type  of  burner  employed. 

The  air  is  controlled  by  the  third  regulator  which  operates  a 
rock  shaft  connected  to  the  dampers  of  all  boilers.  In  this  regu- 
lator the  motion  caused  by  the  diaphragm,  which  is  acted  on  by 
the  oil  pressure,  is  resisted  by  a  coil  spring.  The  amount  of  move- 
ment of  the  lever  is,  therefore,  proportional  to  the  oil  pressure. 


FUEL  OIL  BURNING  APPLIANCES 


219 


This  movement  is  communicated  by  means  of  a  controlling  valve 
and  differential  lever  to  a  hydraulic  cylinder,  which  in  turn  oper- 
ates the  rock  shaft  connected  to  the  dampers. 

A  more  complete  description  of  the  Moore  Automatic  Regu- 
lator will  be  found  in  a  paper  by  C.  R.  Weymouth  on  ''Un- 
necessary Losses  in  Firing  Fuel  Oil"  published  in  Vol.  30  of  the 
Transactions  of  the  American  Society  of  Mechanical  Engineers. 

The  Merit  automatic  oil  stoking  system,  which  is  illustrated 
in  Figs.  143  and  144,  operates  on  the  principle  of  controlling 
the  fires  in  a  series  of  steps,  the  fire  jumping  from  a  small  fire  to 


FIG.   143. — A  typical  automatic  system  of  control. 

Diagrammatic  view,  showing  manner  of  control  for  the  oil,  the  ashpit  and  the  damper: 

A.  Master  controller  E.    Single  bearings  I.     Damper  weights 

B.  Double  oil  strainer  F.    Damper  arms  3.    Interlocking  damper 


C.  Oil  gage 

D.  Regulator 


G.   devices 

H.   Damper  hubs 


K.  Special  brackets 


an  intermediate  fire  and  then  to  the  maximum  fire.  The  oil, 
atomizing  steam  and  air  are  all  three  controlled  by  this  regulator. 
A  diagram  of  this  regulator  is  shown  in  Fig.  143.  The  boiler 
steam  pressure  acts  on  the  diaphragms  of  the  master  controller 
set  shown  in  Fig.  144,  which  consists  of  two  parts,  one  for  the 
maximum  fire  and  one  for  the  medium  fire.  Each  of  these  is 
piped  up  to  a  damper  operating  device,  and  to  a  regulating  device 
on  each  burner,  which  operates  both  the  steam  and  the  oil  valve 
to  the  burner.  For  convenience,  fuel  oil  from  the  main  oil 
supply  pipe  is  used  as  the  operating  fluid,  returning  to  the  oil 


220 


FUEL  OIL  AND  STEAM  ENGINEERING 


pump  suction  when  used.  If  the  boilers  have  full  steam  pressure 
up  they  will  be  working  on  the  small  fire.  If  the  steam  pressure 
begins  to  drop  the  first  master  controller  diaphragm  comes  into 
play,  opening  the  dampers  to  their  medium  position,  and  opening 
the  intermediate  oil  and  steam  valves  to  each  burner.  These 
valves  are  always  open  or  shut,  the  amount  of  opening  being 
fixed  by  adjustable  auxiliary  valves.  If  the  steam  pressure 


FIG.  144. — At  the  Bush  Street  Station  of  the  Great  Western  Power  Company 
in  San  Francisco,  oil  under  pressure  is  used  to  operate  the  regulators  and  the 
interlocking  damper  devices  as  directed  by  the  master  controller  shown  in  the 
illustration.  This  master  controller  controls  the  flow  of  oil  for  the  automatic 
opening  and  closing  of  dampers  and  burners. 

continues  to  drop,  the  second  master  controller  comes  into  play 
opening  the  damper  to  its  full  open  position,  and  opening  the 
remaining  oil  and  steam  valves  to  each  burner,  thus  placing  the 
maximum  fire  in  operation.  This  condition  will  continue  until 
the  steam  pressure  rises  sufficiently  to  shut  off  the  maximum  fire, 
when  the  boilers  will  return  to  the  intermediate  fire,  and  the 
operation  will  be  repeated. 


CHAPTER  XXV 
CHANGING  FROM  COAL  TO  OIL 

When  it  is  contemplated  to  change  from  coal  firing  to  oil  firing, 
the  first  thing  to  be  considered  is  the  relative  cost  of  the  two 
fuels.  This  does  not  mean  merely  the  cost  of  a  ton  of  coal  com- 
pared to  the  cost  of  a  ton  of  oil,  because  oil  has  a  far  greater  heat- 
ing value  than  an  equal  weight  of  coal.  Again,  while  oil  has  a 
fairly  uniform  heating  value,  there  are  great  differences  in  the 
heating  values  of  different  kinds  of  coal.  Consequently  in 
making  the  comparison  it  is  necessary  to  know  the  kind  of  coal 
under  consideration,  and  its  heating  value  per  pound.  Even 
then  we  have  not  gone  quite  far  enough,  for  the  boiler  efficiency 
is  not  the  same  for  all  grades  of  coal,  and  is  higher  for  oil  than  for 
coal.  Thus,  with  a  good  grade  of  semi-bituminous  coal  an 
efficiency  of  75  per  cent,  is  readily  obtainable,  whereas  with  a 
low  grade  bituminous  coal  or  lignite  it  is  difficult  to  obtain  more 
than  60  per  cent,  efficiency  under  ordinary  methods  of  firing. 
With  oil  on  the  other  hand,  tests  have  shown  net  efficiencies  of 
over  80  per  cent,  and  with  careful  operation  it  is  readily  possible 
to  maintain  78  per  cent,  efficiency  in  regular  plant  operation. 

Knowing  the  relative  prices  and  heating  values,  and  the  prob- 
able boiler  efficiency,  it  is  a  simple  matter  to  calculate  the  saving 
that  may  be  effected  by  changing  from  coal  to  oil.  Suppose, 
for  example,  that  the  owner  of  a  plant  is  purchasing  coal  at  $6.00 
per  ton  of  2000  Ib.  and  that  this  coal  contains  6  per  cent,  mois- 
ture and  has  a  heating  value  of  13,000  B.t.u.  per  pound  dry. 
He  is  considering  changing  over  to  oil  which  he  can  purchase  for 
$1.50  per  bbl.  of  42  gal.  The  oil  has  a  gravity  of  16°Be.  and 
therefore  weighs  336  Ib.  per  bbl.;  it  contains  1  per  cent,  water 
and  its  heating  value  when  free  from  water  is  18,500  B.t.u.  per 
pound. 

Since  the  coal  contains  6  per  cent,  moisture  it  is  94  per  cent, 
dry,  and  1  ton  of  coal  contains 

2000  X  0.94  X  13,000  =  24,440,000  B.t.u. 
Similarly  1  bbl.  of  oil  contains 

336  X  0.99  X  18500  =  6,153,840  B.t.u. 
221 


222 


FUEL  OIL  AND  STEAM  ENGINEERING 


If  both  fuels  could  be  burned  with  the  same  efficiency,  then  by 
dividing  24,440,000  by  6,153,840  we  would  find  that  one  ton  of 
coal  is  equivalent  to  almost  4  bbl.  of  oil.  However,  if  the 
oil  can  be  burned  with  an  efficiency  of  78  per  cent,  and  the  coal 
with  an  efficiency  of  only  69  per  cent.,  we  find  that  the  useful 
heat  in  one  ton  of  coal  is 

0.69  X  24,440,000  =  16,863,600  B.t.u. 
and  the  useful  heat  in  1  bbl.  of  oil  is 

0.78  X  6,153,840  =  4,800,000  B.t.u. 

Consequently  one  ton  of  coal  is  equivalent  for  steaming  purposes 
to 


16,863,600 
4,800,000 


=  3.5  bbl.  of  oil 


lu 


11       12 


1234567 

Price  of  Coal-  Dollars  per  Ton  of  2000  Lba. 

FIG.  145. — Comparison  of  fuel  oil  with  coal  of  various  heating  values. 

The  cost  of  3.5  bbl.  of  oil  at  $1.50  per  barrel  is  $5.25,  and  since 
the  coal  costs  $6.00  per  ton,  the  saving  would  be  $0.75  for  each 
ton  of  coal.  If  the  plant  in  question  is  a  100  h.p.  plant,  burn- 
ing, say,  10,000  tons  of  coal  per  year,  the  saving  would  amount 
to  $7500  per  year  for  the  particular  conditions  assumed. 

In  the  set  of  curves  shown  in  Fig.  145  a  comparison  is  given  of 
fuel  oil  with  coal  of  heating  values  varying  from  10,000  to  15,000 
B.t.u.  per  Ib.  The  heating  value  of  the  oil  is  taken  as  18,500 
B.t.u.  per  Ib.  which  is  a  fair  average  value  for  California  oil,  the 
variation  from  this  value  being  small.  The  efficiency  of  78  per 
cent,  for  oil  firing  assumed  in  these  calculations,  can  readily  be 
maintained  in  normal  service  provided  proper  attention  is  paid 
to  the  furnace  design  and  the  regulation  of  the  fires.  In  order 


CHANGING  FROM  COAL  TO  OIL  223 

to  make  this  comparison  fairly  correct  for  the  different  grades 
of  coal,  an  efficiency  of  60  per  cent,  has  been  assumed  for  coal 
having  10,000  B.t.u.  and  75  per  cent,  for  coal  having  15,000  B.t.u. 
per  Ib.  with  intermediate  values  for  coals  that  lie  between  these 
extremes.  As  the  heating  value  of  coal  is  usually  given  on  the 
basis  of  dry  coal,  and  as  coal  when  purchased  invariably  contains 
a  considerable  proportion  of  moisture,  it  has  been  assumed  that 
the  coals  considered  in  this  comparison  contain  6  per  cent, 
moisture.  In  the  case  of  fuel  oil  the  water  content  does  not  usu- 
ally exceed  1  per  cent.,  and  this  value  has  been  assumed  in  the 
comparison.  It  will  be  observed  from  the  diagram  that  oil  at 
$1.50  per  bbl.  is  equivalent  in  price  to  14,000  B.t.u.  coal  at  $6.00 
per  short  ton.  Oil  at  $1.50  per  bbl.  is  also  equivalent  to  12,000 
B.t.u.  coal  at  $4.60  per  short  ton. 

In  addition  to  the  saving  in  cost  of  fuel  there  will  always  be  a 
saving  in  labor  on  changing  from  coal  to  oil,  as  the  operation  of 
firing  is  much  simpler,  there  are  no  expensive  coal  elevators  and 
conveyors  to  be  kept  up  and  there  are  no  ashes  to  handle.  On 
the  other  hand,  the  interest  and  other  fixed  charges  on  the  invest- 
ment required  to  change  over,  reduce  the  saving  to  some  extent. 
Both  of  these  items,  however,  are  small  compared  to  the  cost  of 
fuel,  and  as  they  tend  to  neutralize  each  other  they  may  be  safely 
neglected  except  in  special  cases. 

The  apparatus  required  to  change  a  coal  burning  plant  into  an 
oil  burning  plant  consists  of  the  oil  storage  tank,  oil  pumps,  oil 
heater,  oil  burners  with  the  necessary  interconnecting  piping, 
strainers,  regulating  valves,  etc.,  all  of  which  have  been  described 
in  Chapter  XXIV.  In  addition  an  automatic  oil  firing  system 
may  be  installed  if  desired. 

The  furnaces  under  the  boilers  must  be  altered  to  suit  the  new 
fuel.  If  the  boilers  are  hand  fired  this  is  a  simple  matter,  for 
all  that  is  necessary  is  to  cover  the  grates  with  firebrick,  leaving 
suitable  openings  for  the  admission  of  air,  and  install  the  burners 
properly  housed  and  protected  from  the  heat.  A  furnace  similar 
to  that  illustrated  on  page  158  may  then  be  used,  the  grates 
acting  as  supports  for  the  checkerwork  in  the  furnace  floor. 
Boilers  larger  than  300  h.p.  should  have  a  furnace  length  not  less 
than  10  ft.,  so  in  many  cases  where  the  grates  are  shorter  than 
this  it  will  be  necessary  to  extend '  them.  For  the  additional 
length  necessary  pieces  of  pipe  or  I-beams  may  be  used  to  support 
the  furnace  floor,  instead  of  grates. 


224 


FUEL  OIL  AND  STEAM  ENGINEERING 


BCD 

Jo 


1! 

-rl  ° 


If 

11 


IS 


£     O   fe 

II! 


CD       - 
^    eg 


si 


CHANGING  FROM  COAL  TO  OIL 


225 


FIG.  147. — Oil  fired  steam  heating  station,  Pacific  Gas  and  Electric  Company, 
station  S,  San  Francisco.  B.  &  W.  boilers  are  to  the  left,  fuel  oil  pumps  and 
heaters  in  the  center  background,  feed  water  pumps  and  heater  to  the  right. 


15 


226  FUEL  OIL  AND  STEAM  ENGINEERING 

For  stoker  fired  boilers  the  design  of  furnace  to  be  adopted 
will  depend  largely  on  the  kind  of  stoker,  and  the  arrangement  of 
coal  furnace  and  ashpit.  If  the  use  of  coal  is  to  be  abandoned 
altogether  the  stokers  should  be  removed,  and  an  oil  furnace 
installed  of  the  general  design  indicated  in  Chapter  XX.  If  the 
boilers  are  provided  with  basement  ash  pits  advantage  should  be 
taken  of  this  to  increase  the  furnace  volume  by  placing  the  fur- 
nace floor  below  the  level  of  the  fireroom  floor,  allowing  the  air 
to  come  up  through  the  ashpit  from  the  basement. 

If  oil  is  to  be  used  only  temporarily,  and  it  is  expected  at  some 
future  time  to  go  back  to  coal  burning,  it  will  be  possible  in  many 
cases  to  leave  the  stokers  in  place,  placing  the  oil  burner  at  the 
rear  of  the  furnace,  and  protecting  the  stoker  from  the  heat  by 
means  of  firebrick  supported  by  structural  material,  leaving  a 
dead  air  space  between  the  stoker  and  the  firebrick.  The  prac- 
ticability of  this  arrangement  will  depend  on  the  type  of  stoker, 
kind  of  boiler,  and  space  available,  and  each  case  requires  special 
study  to  secure  the  proper  design. 

The  question  whether  steam  atomizing  or  mechanical  atom- 
izing burners  should  be  adopted  will  depend  on  local  conditions. 
In  general  it  may  be  said  that  steam  atomizers  should  be  used 
wherever  they  are  applicable,  as  they  have  proved  their  practical 
value  by  years  of  application  to  stationary  work.  In  special 
cases  where  steam  atomizers  are  unsuitable  the  mechanical  burner 
may  be  used  to  advantage.  This  would  include  plants  so  located 
that  the  waste  of  fresh  water  is  a  serious  matter.  Plants  in 
which  it  is  necessary  to  force  the  boilers  up  to  300  or  400  per  cent, 
of  their  rated  capacity  may  also  find  the  mechanical  atomizing 
burner  more  suitable,  and  this  will  be  especially  true  if  a  steady 
load  is  carried  and  if  the  plant  is  already  equipped  with  forced 
draft  apparatus. 

Number  of  Men  Required  for  Operating  Oil  Fired  Boilers. — 
The  number  of  men  required  to  operate  boilers  fired  by  oil  is 
much  less  than  the  number  required  to  operate  a  coal  burning 
plant.  In  an  oil  burning  central  station  a  fireman  can  operate 
six  or  seven  large  boilers  having  three  oil  burners  each,  and  in 
addition  attend  to  the  feeding  of  the  boilers  with  water.  In 
other  words,  a  plant  having  26  or  28  boilers  would  require  only 
four  firemen  on  a  watch  besides  a  man  to  look  after  the  feed 
pumps,  oil  pumps  and  keep  records  of  oil  consumption,  tempera- 
tures, etc. 


CHAPTER  XXVI 
THE  GRAVITY  OF  OILS  IN  FUEL  OIL  PRACTICE 

Fuel  oil  is  classified,  marketed,  and  designated  by  its  gravity. 
Gravity  is  denoted  in  two  distinct  ways.  The  scientific  method 
of  notation  is  known  as  the  "  specific  gravity,"  which  is  the  ratio 
of  the  weight  of  a  given  volume  of  the  oil  to  that  of  an  equal  vol- 
ume of  pure  water.  There  has,  however,  grown 
up  in  practice  an  empirical  method  of  repre- 
senting the  gravity  of  oil  by  what  is  known  as 
the  Baume  scale.  This  scale  has  two  separate 
and  distinct  formulas  for  its  conversion  to 
specific  gravity  readings.  One  formula  is  for 
liquids  heavier  than  water  and  the  other  for 
liquids  lighter  than  water.  In  each  instance 
the  scale  is  graduated  to  100  degrees  and  over- 
laps 10  degrees. 

The  use  of  the  Baume  scale  should  be  aban- 
doned as  it  is  not  only  unscientific,  but  con- 
fusing. However,  as  its  use  is  universal  in  the 
oil  industry,  and  it  has  obtained  such  a  firm 
foothold  among  both  producers  and  users  of 
fuel  oil,  it  is  described  and  used  freely  through- 
out this  book. 

Antoine  Baume,  a  French  chemist  of  the 
eighteenth  century,  distinguished  for  his  suc- 
cess in  the  practical  application  of  the  science, 
was  the  inventor  of  the  so-called  Baume  scale 
now  universally  adopted  in  fuel  oil  practice  for 
denoting  the  gravity  of  crude  petroleum. 

The  Scale  for  Liquids  Heavier  Than  Water. — 
Baume  hit  upon  a  unique  plan  for  the  estab- 
lishment of  his  scale.     Certain  fixed  points  were  first  determined 
upon  the  stem  of  the  instrument.     The  first  of  these  was  found 
by  immersing  the  hydrometer  in  pure  water,  and  marking  the 
stem  at  the  level  of  the  surface.     This  formed  the  zero  of  the 

227 


FIG.  148.— Baum6 
hydrometers. 


228 


FUEL  OIL  AND  STEAM  ENGINEERING 


scale.     Fifteen  standard  solutions  of  pure  common  salt  in  water 

were  then  prepared,  containing  respectively  1,  2,  3 15  per 

cent,  (by  weight)  of  dry  -salt.     The  hydrometer  was  plunged  in 
these  in  order  and  the  stem  having  been  marked  at  the  several 

surfaces,  the  degrees  so  obtained  were  numbered  1,  2,  3 15. 

The  instrument  thus  adapted  to  the  determination  of  densities 
exceeding  that  of  water  was  called  the  hydrometer  for  salts. 

Expressed  mathematically  in 
its  relationship  with  the  specific 
gravity  S,  the  Baume  degree 
reading  B  becomes  for  liquids 
heavier  than  water : 
«  145 

"ur^g 

The  Scale  for  Liquids  Lighter 
Than  Water. — Since  practically 
all  grades  of  crude  petroleum 
are  lighter  than  water,  we  are 
most  interested  in  the  method  of 
expression  for  this  latter  phase  of 
gravity  denotation. 

The  original  Baume  hydrom- 
eter  intended   for  densities  less 
than  that  of  water,  or  the  hy- 
drometer  for   spirits,   as  it  was 
called,  was  constructed  on  a  sim- 
ilar   principle    to    that    for   the 
hydrometer     for     salts     above 
was    so   arranged  that   it  floated 
the  stem  above  the  surface.     A 


FJG.    149. — Hydrometer    for  obtain- 
ing gravity  of  fuel  oil. 


described.  The  instrument 
in  pure  water  with  most  of 
solution  containing  10  per  cent,  of  pure  salt  was  used  to  indi- 
cate the  zero  of  the  scale,  and  the  point  at  which  the  instrument 
floated  when  immersed  in  distilled  water  at  10°R.  or  54J^°F. 
was  numbered  10.  Equal  divisions  were  then  marked  off  up- 
wards along  the  stem  as  far  as  the  50th  degree. 

The  Confusion  in  Expression  for  Specific  Gravity  and  Baume 
Readings. — Modern  gravities  are  expressed  for  liquid  tempera- 
tures of  60°F.  instead  of  54K°F.  as  above  set  forth.  This  fact 
together  with  other  inconsistencies  and  errors  in  observation 
have  led  to  the  invention  of  some  seventeen  different  mathemati- 
cal expressions,  by  various  investigators  and  scientific  bodies, 


THE  GRAVITY  OF  OILS  IN  FUEL  OIL  PRACTICE       229 

to  properly  set  forth  a  relationship  between  specific  gravity 
and  Baum6  readings  for  liquids  lighter  than  water.  The  contest 
has  simmered  down  to  two  equations  in  American  practice. 

The  formula  in  general  use  since  1851,  and  which  has  been 
adopted  as  the  "  American  Standard"  by  the  U.  S.  Bureau  of 
Standards  is  as  follows: 

o  140  ,„, 

= 


The  other  formula,  which  is  used  by  C.  J.  Tagliabue  whose 
hydrometers  have  been  adopted  as  standard  by  the  United 
States  Petroleum  Association,  is  as  follows  : 

141.5 
131.5  +  B 

A  full  discussion  of  the  relative  merits  of  these  two  formulas  is 
given  in  Circular  No.  59  of  the  Bureau  of  Standards  from  which 
the  following  extract  is  taken: 

"At  the  time  the  Bureau  of  Standards  was  contemplating 
taking  up  the  work  of  standardizing  hydrometers  (about  1904), 
diligent  inquiry  was  made  of  the  more  important  American  manu- 
facturers of  hydrometers  as  to  the  Baume  scales  used  by  them. 
Without  exception  they  replied  that  they  were  using  the  modulus 
145  for  liquids  heavier  than  water,  and  140  for  liquids  lighter 
than  water.  These  scales,  the  "  American  standard,"  were  there- 
fore adopted  by  the  Bureau  of  Standards  and  have  been  in  use 
ever  since. 

There  having  been  no  objection  or  protest  from  any  manu- 
facturer or  user  of  Baume  hydrometers  at  the  time  the  scales 
were  adopted  by  the  Bureau,  it  was  assumed  that  they  were  en- 
tirely satisfactory  to  the  American  trade  and  were  in  universal 
use.  Such,  in  fact,  appears  to  be  the  case  with  the  scale  for 
liquids  heavier  than  water,  but  in  the  case  of  the  scale  for  liquids 
lighter  than  water  a  disturbing  element  has  arisen  which  threat- 
ens to  some  extent  the  uniform  practice  that  has  heretofore 
existed. 

The  exact  date  of  this  disturbing  influence  can  not  be  fixed 
with  certainty,  but  it  was  first  noticed  some  four  or  five  years 
ago,  and  has  been  quietly  at  work  since  then  to  break  down  the 
uniformity  of  practice  previously  existing  and  to  counteract 
as  far  as  possible  the  influence  of  the  Bureau  of  Standards  in 
the  interest  of  uniformity. 


230  FUEL  OIL  AND  STEAM  ENGINEERING 

It  appears  that  a  certain  manufacturer  of  hydrometers,  es- 
pecially those  used  in  the  oil  trade,  discovered  that  his  Baume 
hydrometers  were  not  graduated  in  accordance  with  the  American 
standard  Baume  scale  in  general  use  based  on  the  modulus  140. 
This  discovery  made  necessary  for  the  manufacturer  one  of  two 
things:  Either  he  must  consider  his  ijistruments  in  error,  by  the 
amount  of  the  difference,  or  he  must  change  the  basis  of  the  scale 
to  conform  to  his  instruments.  The  manufacturer  in  question, 
C.  J.  Tagliabue,  chose  the  latter  course. 

The  developments  of  the  problem  confronting  Mr.  Tagliabue 
are  well  shown  by  the  various  editions  of  his  Manual  for  Coal 
Oil  Inspectors.  The  first  few  editions  of  this  publication  con- 
tained the  regular  American  standard  Baume  table,  modulus  140. 
Then  came  the  discovery  that  his  instruments  did  not  fit  the 
table,  and  an  attempt  was  made  to  make  a  table  to  fit  the  instru- 
ments. The  result  was  an  irregular  table  with  no  definite 
modulus.  This  was  published  in  at  least  two  editions  of  the 
manual.  Then  followed  the  table  which  is  now  published  by  Mr. 
Tagliabue  in  the  eighth  edition  of  his  manual,  based  on  the 
modulus  141.5,  which  more  nearly  fits  his  standard  hydrometers 
for  petroleum  oil. 

A  small  pamphlet  prepared  by  Mr.  Tagliabue  has  recently 
been  widely  distributed  in  which  the  impression  is  given  that 
the  modulus  141.5  was  adopted  by  the  United  States  Petroleum 
Association  in  1864,  and  has  been  in  use  in  the  petroleum  trade 
ever  since,  and  that  lately  the  modulus  140  has  been  proposed 
and  that  great  confusion  may  result  from  its  use.  That  such  is 
by  no  means  the  case  has  been  shown  by  the  foregoing  references 
and  historical  matter. 

There  can  be  little  doubt  that  when  the  United  States  Petro- 
leum Association  adopted  as  standard  the  hydrometers  made 
by  Jarvis  Arnaboldi,  who  was  later  succeeded  by  C.  J.  Tagliabue, 
it  was  believed  by  all  concerned  that  the  instruments  were  based 
on  the  American  Standard  Baume  scale." 

The  Limitations  of  the  Hydrometer. — The  hydrometer  method 
of  ascertaining  the  gravity  of  crude  petroleum  is  at  best  only 
approximate,  as  one  may  readily  surmise.  In  order  then  to 
ascertain  the  gravity  of  oil  with  scientific  accuracy,  a  more 
refined  method  is  necessary.  This  is  usually  accomplished  by 
determining  the  specific  gravity  of  the  oil  with  whatever  moisture 
content  it  may  contain  by  means  of  an  actual  water  equivalent 


THE  GRAVITY  OF  OILS  IN  FUEL  OIL  PRACTICE       231 

comparison,  and  then  converting  this  into  degrees  Baume*.  This 
roundabout  method  once  again  emphasizes  the  uselessness  of 
employing  the  Baume  scale.  If  the  moisture  content  of  the  oil 
has  been  ascertained,  a  computation  is  then  made  in  order  to 
arrive  at  the  actual  specific  gravity  or  Baume*  reading  for  the 
moisture  free  oil. 

The  Method  of  the  Westphal  Balance  for  Exact  Measurement. 
Let  us  then  examine  in  detail  such  a  method.     The  Westphal 


FIG.  150. — A  commercial  balance  for  determining  specific  gravity  of  oil. 

The  common  hydrometer  is  not  of  sufficient  accuracy  to  determine  the  specific  gravity 
of  oil  used  in  fuel  oil  tests.  A  simple  and  accurate  method  for  such  determination  is  accom- 
plished by  the  employment  of  a  Westphal  Balance  as  shown  in  the  illustration.  The  spe- 
cific gravity  is  first  ascertained  by  comparison  of  the  oil  with  a  water  standard  and  then  by 
means  of  the  mathematical  relationship  connecting  specific  gravities  and  Baume  readings, 
the  latter  gravity  reading  is  ascertained. 

balance  is  a  convenient  and  accurate  method  by  which  the  specific 
gravity  of  fuel  oil  may  be  obtained  to  four  decimal  points.  As 
shown  in  Fig.  150,  the  apparatus  necessary  consists  of  a 
balance  arm,  supported  on  knife  edges,  from  one  end  of  which  is 


232  FUEL  OIL  AND  STEAM  ENGINEERING 

hung  a  glass  bulb,  the  other  end  being  counter-weighted.  Along 
the  balance  arm  are  nine  notches,  the  hook  supporting  the  glass 
bulb  being  in  the  position  of  the  tenth  notch.  The  glass  bulb  has 
a  displacement  of  exactly  five  grams  of  pure  water  at  4°C.,  which 
is  the  point  of  maximum  density  of  water,  the  density  for  which 
scientific  gravity  comparisons  are  made.  Hence  if  the  bulb  above 
described  were  so  immersed  in  water  at  4°C.  a  five  gram  weight 
would  establish  equilibrium  if  hung  from  the  hook.  This  would 
indicate  a  specific  gravity  of  1.0000. 

The  zero  point  of  the  balance  is  adjusted  by  turning  a  thumb 
screw,  which  forms  one  point  of  the  three  point  support  shown  in 
the  figure,  until  the  pointers  are  opposite  each  other  before  the 
bulb  is  immersed.  For  specific  gravities  less  than  1.0000  the 
five  gram  rider  called  the  unit  weight  is  hung  in  a  notch  such  that 
equilibrium  is  nearly  reached,  never  exceeded.  This  gives  the 
first  decimal  place.  The  KO,  Koo>  and  Mooo  unit  weights 
are  then  hung  respectively  in  notches  so  that  equilibrium  is 
finally  established.  The  specific  gravity  is  then  read  directly  to 
four  decimal  places  by  noting  the  notches  in  which  the  riders 
hang,  commencing  with  the  largest  rider.  Thus  when  the  unit 
weight  hangs  in  the  ninth  notch,  the  Jf  o  weight  in  the  sixth 
notch,  the  Hoo  weight  in  the  seventh  notch,  and  the  Mooo 
weight  in  the  third  notch,  the  specific  gravity  is  evidently  0.9673. 

Details  of  Procedure. — Before  proceeding  with  a  gravity 
determination,  the  oil  sample  should  be  allowed  to  stand  in  the 
laboratory  several  hours  in  order  that  any  drops  of  water  in  the 
oil  may  settle.  A  small  quantity  is  then  poured  from  the  sample 
can  into  a  suitable  glass  jar.  The  Westphal  balance,  having 
been  dusted  with  a  soft  brush,  is  then  adjusted  to  equilibrium  and 
the  specific  gravity  of  the  sample  obtained.  The  temperature  is 
also  ascertained  by  means  of  the  thermometer  inserted  in  the 
oil  sample.  Since  specific  gravities  of  fuel  oil  are  by  common 
practice  referred  to  at  a  temperature  of  60°F.,  it  is  now  necessary 
to  make  a  second  determination  at  a  temperature  differing  by 
15°  to  20°F.  from  the  first,  in  order  that  we  may  have  sufficient 
data  with  which  to  compute  what  the  gravity  would  be  at  60°F. 
temperature. 

To  take  this  second  reading  the  temperature  of  the  sample  in 
the  jar  may  be  raised  by  immersion  in  a  water  bath.  In  doing 
this  great  care  must  be  taken  to  allow  no  water  to  get  into  the 
oil. 


THE  GRAVITY  OF  OILS  IN  FUEL  OIL  PRACTICE       233 

Computations  Involved.  —  Let  us  next  illustrate  the  computa- 
tions involved  in  a  gravity  determination.  Let  us  assume  that  by 
means  of  the  Westphal  balance,  the  oil  sample  is  seen  to  have  a 
specific  gravity  (/Si)  of  0.9644,  at  a  temperature  (ti)  of  68.9°F.,  and 
a  specific  gravity  (£2)  of  0.9587  at  a  temperature  (Z2)  of  86.6°F. 
Since  the  specific  gravity  has  changed  ($1  —  82)  over  a  tempera- 

/  Cf    _  O    \ 

ture  change  of  (ti  —  k)  the  change  for  1°F.  would  be  -77^  —  rr— 

(ti  —  12) 

This   change  in  specific  gravity  for  1°F.  is  the  coefficient  of 
expansion  (Ce)  ,  for  the  oil  and  may  be  expressed  by  the  formula 

..  (Surjy  ,4 

(«i-«») 

In  the  particular  case  then  we  now  find  that 


The  coefficient  is  thus  seen  in  this  case  to  represent  an  intermedi- 
ate value,  for  in  practice  we  find  that  in  different  oils  Ce  varies 
from  (-0.00027)  to  (-  0.00042). 

From  the  fundamental  definition  of  the  coefficient  of  expansion 
it  is  now  seen  that  at  60°F.,  the  specific  gravity  becomes 

S  =  S,  +  Ce(60  -  <0  (5) 

Consequently  by  making  the  proper  substitutions  for  the  case 
cited  we  find  that  the  numerical  value  of  the  specific  gravity 
of  this  oil  sample  for  60°F.  is 

S  =  0.9644  +  [  -  0.000322  X  (  -  8.9)]  =  0.9673 

In  order  to  convert  this  specific  gravity  to  the  Baume  scale 
we  now,  by  substituting  in  formula  given  above  for  such  conver- 
sion, find  that 

B  -       -  13°  -  14-73° 


Assuming  that  this  particular  oil  sample  has  been  found  to 
contain  0.5  per  cent,  by  weight  of  moisture  and  0.484  per  cent. 
by  volume,  let  us  now  see  how  we  should  find  the  specific  gravity 
of  the  dry  oil.  Let  Vw  represent  the  percentage  of  water  by 
volume  and  Sw,  S0,  Sm  represent  respectively  the  specific  gravity 
of  the  water,  dry  oil,  and  moisture.  Then  we  may  write  the 
following  relationship  : 

/100  —  Vw\        „   I  Vw 

s-  -  &(—  i66~~y  + 


234  FUEL  OIL  AND  STEAM  ENGINEERING 

From  scientific  tables  we  find  that  Sw  at  60°F.  has  a  value  of 
0.9990,  and  from  the  Westphal  balance  Sm  has  been  found  to  be 
0.9673.  By  transforming  the  formula  above  it  is  seen  that 


s,  -  (7) 


Consequently  S0  may  now  be  computed  numerically. 
_  0.9673  -  0.00484  X  0.9990 
1.00  -  0.00484 

If  it  is  desirable  to  ascertain  the  Baume  reading  for  the  dry 
oil,  we  next  ascertain  its  value  from  the  above  relationship  of 
specific  gravity  and  the  Baume  scale  from  equation  (2). 


According  to  formula  (3)  this  Baume*  reading  would  of  course 
be  computed  as  follows: 

B  =  -  131.5  =  --  131.5  =14.8° 


When  a  large  quantity  of  oil  is  to  be  purchased  and  it  is  desirable 
to  carry  the  Baume*  reading  to  still  further  decimal  points,  the 
two  formulas  will  not  of  course  check;  hence,  one  or  the  other  of 
these  formulas  should  be  agreed  upon  prior  to  a  purchase  of  any 
magnitude. 


CHAPTER  XXVII 
MOISTURE  CONTENTS  OF  OILS 

From  our  previous  discussion  of  steam  generation  in  the  mod- 
ern central  station  it  was  found  that  something  over  a  thousand 
heat  units  are  necessary  to  convert  one  pound  of  water  at  ordi- 
nary temperatures  into  saturated  steam.  When  moisture  appears 
in  the  oil  used  for  heat  generating  purposes  in  the  furnace  it  is 
evident,  then,  that  large  heat  losses  may  thereby  be  involved. 
For,  not  only  must  this  moisture  be  con- 
verted into  saturated  steam,  but  this 
steam  itself  must  be  superheated  to  the 
temperature  of  the  outgoing  chimney 
gases,  thus  dissipating  energies  that 
should  go  toward  steam  generation  in 
the  boiler. 

Hence  the  water  involved  in  fuel  oil 
composition  is  a  dead  loss  which  should 
be  avoided  as  far  as  possible.  Settling 

,  ,.  ,  i      •        i*        •  ^   FIG.  151.—  An   electrically 

tanks    accomplish    much  in  drawing  off       driven  oil  centrifuge. 
the   water  content,  but  when  the  water      in  this  centrifuge  the  four 

,1  -i  ,    .  .        .       arms  —  two  plain  and  two  grad- 

in    the    Oil    aS    an    emulsion    it     IS    uated—  are  caused  to  rotate  by 


,      •  •-,  -,  '-I-,  electric   power   and   the   water 

almost  impossible  to  commercially  segre-  thus  caused  to  separate  from 
gate  it  from  the  oil.     Since,  then,  all  fuel  urement  of  the  "iSS 


•i  ,     •  ,     •  it-  •    i  ent  is  then  easily  ascertained. 

oils  contain  a  certain  amount  of  moisture, 

the  careful  determination  of  its  exact  proportions  often  becomes 

an  important  problem  in  efficient  steam  engineering  performance. 

Summary  of  Methods  Employed  in  Determining  the  Moisture 
Content.  —  There  are  ten  methods  by  which  the  moisture  content 
of  oil  can  be  ascertained  with  approximate  accuracy.  For 
detailed  information  on  this  subject  the  reader  is  referred  to  Tech- 
nical Paper  No.  25  of  the  United  States  Bureau  of  Mines  en- 
titled, "  Methods  for  the  Determination  of  Water  in  Petroleum 
and  its  Products."  These  methods  may  be  briefly  summarized 
as  follows: 

The  moisture  content  of  heavy  oils  and  greases  may  be  approxi- 
mately ascertained  by  the  loss  of  weight  due  to  heating. 

235 


236  FUEL  OIL  AND  STEAM  ENGINEERING 

The  moisture  content  of  oil  may  be  approximately  obtained 
by  diluting  a  sample  with  a  sulphate  and  then  causing  separation 
by  action  of  gravity.  A  diluent  is  to  be  avoided  in  this  process, 
as  inaccuracies  are  liable  to  be  introduced. 

Again  by  diluting  with  a  solvent  and  separating  the  moisture 
content  by  means  of  a  centrifuge,  the  moisture  content  is  de- 
termined with  a  slightly  greater  degree  of  accuracy  than  by  either 
of  the  above  methods. 

By  treating  a  sample  with  calcium  carbide,  another  convenient 
method  is  also  arrived  at,  and  its  accuracy  is  approximately 
within  3  per  cent,  of  the  water  percentage  if  care  is  observed. 
The  sample,  too,  may  be  treated  with  sodium  and  a  convenient 
and  accurate  method  results. 

A  color  comparator  is  sometimes  used,  but  the  method  is  only 
approximate,  as  is  also  the  method  of  treating  a  sample  with 
normal  acids.  The  electrical  treatment,  on  the  other  hand,  is 
successful  in  breaking  up  an  emulsion  on  a  commercial  scale,  or 
reducing  the  water  content  of  an  oil  to  such  a  condition  that  it 
may  be  successfully  treated  in  some  other  manner.  An  emulsion 
is  a  physical  condition  of  the  oil  and  water  wherein  the  water  is 
held  in  such  intimate  content  with  the  oil  ingredients  as  not  to  be 
readily  separated  by  gravity  or  other  ordinary  means. 

Again,  too,  distilling  a  sample  mixed  with  a  non-miscible  liquid 
proves  accurate  to  0.033  grams  of  water  per  100  cc.  of  benzine  and 
oil  in  the  distillate. 

The  most  reliable  method,  however,  is  that  accomplished  by 
directly  distilling  off  the  water.  This  method  is  convenient  and 
accurate  to  about  0.003  grams  of  water  in  the  distillate,  if  the 
water  is  cooled  to  about  35°F. 

The  Approximate  Method  of  Treatment. — The  method  hinted 
at  above  wherein  the  sample  is  treated  by  a  foreign  agent  will 
now  be  briefly  set  forth,  since  such  a  preliminary  determination 
often  proves  sufficiently  accurate  for  the  issues  involved. 

The  method  here  outlined  is  especially  applicable  for  the  lighter 
oils.  A  burette  graduated  into  200  divisions  is  filled  to  the  100 
mark  with  gasoline,  and  the  remaining  100  divisions  with  the  oil, 
which  should  be  slightly  warmed  before  mixing.  The  two  are 
then  shaken  together  and  any  shrinkage  below  the  200  mark 
filled  up  with  the  oil.  The  mixture  should  then  be  allowed  to 
stand  in  a  warm  place  for  24  hr.,  during  which  the  water  and  silt 
will  settle  to  the  bottom.  Their  percentage  by  volume  can  then 


MOISTURE  CONTENTS  OF  OILS 


237 


be  correctly  read  on  the  burette  divisions,  and  the  percentage  by 
weight  calculated  from  the  specific  gravities. 

Details  Involved  in  Determination  of  Distillation. — Since  the 
method  of  determination  by  distillation  is  to  be  recommended 
above  all  others,  we  shall  now  proceed  to  the  details  of  its  ac- 
complishment. Stated  in  simple  words,  the  method  consists  in 
heating  a  sample  slightly  above  the  boiling  point  of  water  but 
not  so  high  as  to  cause  the  vaporizing  of  other  ingredients  of  the 
oil.  As  a  consequence,  the  water  passes  over  and  leaves  water- 
free  oil  in  the  sample. 


FIG.   152. — A  Goetz  attachment  for  water  determination. 

By  attaching  the  pipe  shown  in  the  lower  part  of  the  figure  to  a  faucet,  sufficient  power  is 
obtained  from  the  city  main  to  cause  the  rapid  rotation  of  the  two  aims  shown  in  the  figure. 
This  highrotative'speed,  due  to  the  centrifugal  force  developed,  causes  the  separation  of  the 
moisture  from  the  oil. 

The  Apparatus  Involved  and  Preliminary  Proceedings. — To 

quantitatively  determine  the  moisture  content  the  sample  is 
placed  in  a  copper  vessel  known  as  a  still,  which  is  about  4  in. 
in  diameter  and  6  in.  high.  The  still  is  then  placed  in  an  asbestos 
hood  through  which  a  projecting  stem  connects  to  a  condenser 
and  a  burette  where  the  condensate  is  measured  in  a  graduated 
tube.  The  can  from  which  the  sample  is  to  be  drawn  is  first 
immersed  in  a  water  bath  with  its  cover  released.  After  the  water 
constituting  the  bath  has  been  raised  to  a  temperature  of  150° 
to  170°F.,  the  cover  to  the  can  is  fastened 'tightly,  and  the  can 
agitated  for  several  minutes  in  order  that  any  water  that  may 
have  settled  at  the  bottom  may  be  thoroughly  mixed  with  the 
oil.  For  successful  agitation  the  sample  can  should  not  be  filled 
more  than  two-thirds  with  oil.  100  cc.  of  oil  sample,  measured 
in  a  graduated  jar,  are  now  poured  into  the  still.  The  exact 
measurement  of  the  oil  is  difficult  without  experience,  as  froth 


238 


FUEL  OIL  AND  STEAM  ENGINEERING 


collects  on  the  surface  of  the  oil  and  tends  to  obscure  any  definite 
meniscus. 

The  jar  is  next  washed  with  50  cc.  of  benzol  and  50  cc.  of 
toluene.  The  washings  are  poured  into  the  still.  Since  toluene 
has  a  tendency  to  absorb  small  quantities  of  water,  accurate 
results  may  be  interfered  with  if  the  toluene  is  not  previously 


FIG.  153. — Still  with  hood  used  for  water  determination. 

Many  methods  are  utilized  in  determining  the  water  content  of  oil.  The  simplest  and 
most  accurate  method  for  fuel  oil  tests  is  that  of  distillation.  In  this  method  a  sample  of 
the  oil  is  poured  into  a  still  and  raised  sufficiently  in  temperature  to  evaporate  the  water 
and  not  the  ingredients  of  the  oil.  By  condensing  the  moisture  and  ascertaining  its  pro- 
portions the  moisture  content  is  easily  ascertained. 


saturated.  In  order  to  avoid  such  a  possibility  when  opening  a 
fresh  bottle,  5  to  10  cc.  of  water  should  be  added.  The  presence 
of  water  in  the  bottom  of  the  bottle  shows  that  the  toluene  is 


MOISTURE  CONTENTS  OF  OILS  239 

saturated,  but  care  must  be  taken  not  to  pour  this  water  into  the 
still  when  washing  with  the  toluene. 

The  still  must  be  gently  shaken  without  splashing  in  order  that 
its  contents  may  be  well  mixed,  and  then  placed  in  the  asbestos 
hood  and  connected  with  the  condenser.  A  hood  and  cover  are 
provided,  as  shown  in  the  illustration,  to  surround  the  still  with 
a  blanket  of  air  at  a  uniform  temperature.  The  still  is  then 
heated  gradually  to  a  temperature  of  about  300°F.,  which  is 
usually  accomplished  after  about  fifteen  minutes  of  heating. 
Since  the  boiling  point  of  water  has  been  now  exceeded,  the  mois- 
ture in  the  sample  begins  to  pass  over  into  the  condenser,  and  after 
the  lapse  of  another  fifteen  minute  period  the  distillation  is  com- 
plete. A  thermometer  for  temperature  control  is  seen  at  the 
right  side  of  the  asbestos  hood  in  the  illustration. 

The  Process  of  Distillation. — The  process  of  distillation  is 
interesting.  At  about  176. 7°F.  the  benzol  first  passes  over.  This 
wets  the  condenser  tube  so  that  the  moisture  which  is  soon  to 
follow  will  not  readily  cling  to  the  tube  but  the  more  easily 
pass  down  into  the  measuring  burette.  The  toluene  follows  at 
230. 5°F.,  and  carries  down  with  it  any  water  which  happens  to 
remain  in  the  condenser  tube.  The  toluene  does  not,  however,  pass 
over  in  its  entirety,  since  usually  from  15  to  20  cc.  remain  in  the 
still  with  the  oil.  In  order  to  make  up  this  deficiency  in  toluene 
about  15  cc.  are  poured  down  the  condenser  tube  to  free  any 
small  drops  of  water  that  may  persist  in  remaining.  This,  how- 
ever, does  not  affect  the  accuracy  of  the  work,  since  the  water 
content  is  finally  separated  by  filtration  and  the  water  content 
thus  obtained  is  alone  measured. 

The  still  while  at  a  high  temperature  is  drained,  and,  as  its 
contents  are  now  entirely  free  from  water,  it  may  be  used  again 
without  additional  cleaning. 

Any  small  drops  of  water  that  cling  to  the  side  of  the 
graduated  measuring  tubes  must  be  released  by  a  short 
wire.  If  now  the  resultant  water  is  read  in  cc.  the  percentage 
of  water  by  volume  in  the  oil  is  easily  obtained,  since  the  water 
is  separated  from  the  mixture  of  benzol  and  toluene  in  the  filter 
bottle. 

A  Numerical  Determination: — Let  us  then  follow  this  process 
by  means  of  an  illustrative  example.  Let  us  assume  that  100  cc. 
of  oil  have  been  drawn  as  a  sample,  that  100  cc.  of  benzol  and 
toluene  have  been  poured  with  it  into  the  still,  and  that  the 


240  FUEL  OIL  AND  STEAM  ENGINEERING 

resultant  distillate  shows  0.484  cc.  of  water.  It  then  follows 
directly  that  the  percentage  of  water  by  volume  is  0.484. 

Error  in  Assuming  Percentage  by  Weight  is  Same  as  Percent- 
age by  Volume. — The  percentage  of  water  by  weight  is  not 
exactly  equal  to  its  percentage  by  volume,  but  may  be  taken  equal 
to  it  for  all  practical  purposes  of  boiler  testing.  This  error  is  then 
nominal  except  with  very  light  oils  or  any  oil  with  considerable 
moisture  content.  Thus,  if  an  oil  sample  of  100  cc.  contains 
0.50  cc.  of  water  at  60°F.,  it  will  weigh  0.484  X  0.999  =  0.4835  grm. 

The  percentage  of  water  by  weight  is  therefore  0.4835  divided 
by 0.9673,  which  equals  0.50  percent.  The  factor,  0.9673,  appear- 
ing in  the  above,  is  the  specific  gravity  of  the  oil  sample  at  60°F. 
.This  was  ascertained  by  means  of  a  Westphal  balance,  which  is 
shown  in  detail  in  the  preceding  chapter. 


CHAPTER  XXVIII 
DETERMINATION  OF  HEATING  VALUE  OF  OILS 

To  determine  the  efficiency  of  boiler  operation  it  is  necessary 
to  know  the  heat  producing  value  of  the  oil  used  in  firing.  Again, 
since  oil  is  usually  sold  commercially  by  the  barrel,  the  heat 
producing  value  of  the  product  must  be  known  in  order  that  the 


24 
23 

HZ 

20 
19 

id 

17 
16 
13 
14 
13 
12 
II 

10 
«7< 

/ 

•/ 

7 

/ 

y 

1 

y 

$ 

V 

o 

/ 

0 

0 

r° 

c 

o 

? 

'\. 

>o° 

& 

O 

o 

/ 

c 

0 

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f 

MO                  18000                   18506                   19500                  13500                   201 

FIG.   154. — The  Graphic  Law  for  calorific  value  of  fuels. 

In  this  illustration  is  shown  how  a  large  number  of  experimental  values  often  enable  the 
engineer  to  ascertain  an  empirical  law  for  setting  forth  experimental  data.  By  plotting  the 
heat  determinations  for  fuel  oil  against  their  gravity  expressed  in  Baum6  readings,  the 
experimenter  deduced  an  equation  for  determining  the  calorific  value  of  water  free  oil  when 
its  gravity  BaumS  is  known. 

engineer  may  ascertain  the  economic  value  the  product  may  prove 
to  his  client  in  its  use  in  the  power  plant  for  the  generation  of 
steam. 

16  241 


242  FUEL  OIL  AND  STEAM  ENGINEERING 

An  Approximate  Method  Based  on  the  Baume   Scale. — The 

heat  producing  value  of  oil  is  usually  expressed  in  the  number  of 
heat  units  per  unit  of  mass  that  the  oil  will  give  out  when  it  is 
completely  burned  in  a  furnace.  In  engineering  practice  this  is 
usually  expressed  in  B.t.u.  per  pound  of  oil  so  burned. 

There  are  various  methods  of  ascertaining  this  value.  An 
approximate  method  is  that  based  upon  the  gravity  of  the  oil. 
To  establish  this  method  a  large  number  of  samples  with  the 
gravities  of  the  oil  free  from  moisture  expressed  in  Baume"  readings 
were  accurately  determined  as  to  their  heating  value.  These 
values  were  plotted  on  a  chart  and  it  was  found  that  the  following 
relationship  is  approximately  true  in  which  H  represents  the 
heat  units  in  B.t.u.  liberated  per  pound  of  fuel  burned,  and  B 
represents  the  gravity  of  the  oil  in  degrees  Baume": 

H  =  17680  +  60£  (1) 

Thus  in  analyzing  a  composite  sample  of  forty  samples  of 
Kern  River  oil,  the  United  States  Bureau  of  Mines  found  that  its 
calorific  value  was  18,562  B.t.u.  per  Ib.  of  oil,  in  which  the  oil  had 
0.5  per  cent,  moisture,  and  that  the  Baume*  reading  of  this  oil 
when  free  from  water  was  14.78°.  According  to  the  formula 
above,  which  was  first  announced  by  Professor  Joseph  N.  LeConte 
of  the  University  of  California,  the  heating  value  of  this  oil  when 
free  from  moisture  should  be 

H  =  17680  +  60  X  14.78  =  18,566  B.t.u.  per  Ib. 

In  this  instance  then  it  is  seen  that  this  approximate  method 
checks  with  considerable  accuracy,  since  the  water-free  oil 
showed  by  actual  test  to  have  a  heating  value  of  18,658  B.t.u. 
per  Ib.  In  the  utilization  of  this  formula,  however,  it  must  be 
remembered  that  the  oil  must  be  taken  as  anhydrous,  or  in  other 
words  that  the  oil  sample  is  moisture  free. 

Dulong's  Formula  Based  on  the  Ultimate  Analysis. — The 
second  method  of  arriving  at  the  calorific  value  of  crude  petro- 
leum is  by  means  of  Dulong's  formula.  This  formula  is  based 
upon  the  ultimate  analysis  of  the  oil  in  which  the  heat  value  of 
carbon,  hydrogen,  and  sulphur  are  taken  into  account. 

In  the  burning  with  oxygen  of  one  pound  of  carbon,  one  pound 
of  hydrogen,  and  one  pound  of  sulphur  it  has  been  established 
experimentally  that  14,600,  62,000,  and  4000  B.t.u.  of  heat  energy 
are  respectively  given  out.  Hence  it  is  evident  that  if  a  one- 


DETERMINATION  OF  HEATING  VALUE  OF  OILS       243 


pound  sample  of  fuel  oil  has  C  proportions  by  weight  of  carbon, 
H  proportions  by  weight  of  hydrogen  and  S  proportions  by  weight 
of  sulphur,  the  total  heat  given  out  by  the  one-pound  sample 
will  be 

H  ==  14,600C  +  62,000#  +  40005 

In  the  chemical  analysis  of  fuels  a  certain  amount  of  oxygen 
(0)  is  always  encountered.  This  of  course  kills,  as  it  were,  its 
combining  weight  of  hydrogen.  Since  oxygen  unites  with  one- 
eighth  of  its  weight  of  hydrogen,  the  net  hydrogen  available  for 

heat  generating  purpose  is  \H  —  g 


Hence  we  have  Dulong's  formula 

H  =  14,600C  +  62,000  (H  -  °]  +  40005 


(2) 


FIG.   155. — The  Emerson  fuel  calorimeter. 

In  this  type  of  calorimeter  the  fuel  sample  is  placed  in  the  bomb,  the  bomb  inverted,  as 
shown  in  the  sketch,  and  filled  with  oxygen  which  is  accomplished  by  means  of  the  spindle 
valve  at  the  top  of  the  bomb.  After  filling  the  calorimeter  with  distilled  water  and  firing 
the  sample  by  means  of  an  electric  circuit,  the  rise  in  temperature  of  the  water  in  the  calor- 
imeter is  ascertained,  and  the  calorific  value  of  the  fuel  thus  determined. 


For  California  oils,  Dulong's  formula  seems  to  indicate  a  heat 
value  per  pound  of  about  5  per  cent,  in  excess  of  the  true  value. 
In  other  words,  it  indicates  a  heating  value  of  about  19,500  B.t.u. 
per  pound  of  California  crude  oil,  while  a  great  number  of 
calorific  tests  have  shown  that  the  average  value  is  about  18,500 
B.t.u.  per  pound. 


244 


FUEL  OIL  AND  STEAM  ENGINEERING 


The  Fuel  Calorimeter. — The  most  accurate  method  of  deter- 
mining the  heating  value  of  a  sample  of  oil  is  by  the  employment 
of  some  form  of  calorimeter,  wherein  a  sample  of  definite  mass 
is  burned  and  the  heat  given  out  ascertained.  The  fuel  calori- 
meter is  an  entirely  different  instrument  from  the  steam  colori- 
meter used  for  measuring  the  moisture  of  steam,  which  was 

described  in  an  earlier  chapter.  The 
fuel  calorimeter  is  a  true  instrument 
for  measuring  heat  as  its  name  implies. 
Calorimeters  in  general  may  be  divided 
into  two  classes,  the  one  known  as  the 
continuous  method  and  the  other  as 
the  discontinuous  method.  In  the 
former  instance  a  sample  is  continually 
burned,  and  the  average  results  ascer- 
tained over  a  considerable  period. 
This  method  is  only  applicable  for 
gases  and  some  unusual  types  of  oils. 
The  discontinuous  process  is  on  the 
other  hand  the  most  advantageous  for 
the  determination  of  the  heating  value 
of  crude  petroleum. 

Several  methods  are  employed  in  the 
application  of  the  discontinuous  calori- 
meter. Most  forms  of  such  calori- 
meters consist  essentially  of  a  strong 
combustion  chamber  with  a  crucible  for 
holding  the  sample;  valves  for  charging 
the  chamber  with  oxygen  in  order  to 
properly  burn  the  sample;  a  method  of 
igniting  the  sample;  and  a  vessel  of 
water  in  which  the  bomb  or  explosion 
in  order  that  the  resultant  heat  may 
water  and  thus  carefully  measured. 


FIG.    156.— The    Atwater- 
Mahler  bomb  calorimeter. 

This  type  of  calorimeter  is 
applicable  to  the  highest  scien- 
tific work.  It  permits  of  deter- 
mining the  exact  amount  of 
water  and  carbon  dioxide  in 
the  products  of  combustion, 
thus  enabling  the  error  due  to 
the  condensation  of  the  water 
in  the  bomb  to  be  overcome 
and  therefore  making  it  pos- 
sible to  calculate  the  exact 
amount  of  heat  the  fuel  should 
produce  under  boilerconditions. 


chamber  is  immersed 
be  absorbed  by  this 
This  latter  vessel  is  usually  situated  in  a  second  compartment 
which  serves  as  a  jacket.  The  main  principle  upon  which  such 
calorimeters  depend  is  based  upon  the  fact  that  the  burning  of 
carbon,  hydrogen,  and  sulphur  with  an  artificial  supply  of  oxygen 
presents  the  most  accurate  method  of  liberating  the  latent  heat 
in  the  fuel  and  the  ascertaining  of  its  quantitative  proportions. 
Types  of  this  calorimeter  familiar  in  the  market  are  known  as 


DETERMINATION  OF  HEATING  VALUE  OF  OILS       245 


the  Mahler,  the  Hempel,  the  Atwater,  the  Emerson,  and  the 
Carpenter. 


FIG.  157. — The  Mahler  bomb  calorimeter. 

This  type  of  calorimeter  represents  one  of  the  most  accurate  for  the  determination  of  the 
calorific  value  of  fuel  oil.  The  bomb  is  of  enameled  steel.  The  burning  of  the  oil  sample 
is  accomplished  by  supplying  an  outside  source  of  oxygen  as  in  the  Emerson  Calorimeter. 

The  Parr  Calorimeter. — In  the  commercial  determination  of 
the  heating  value  of  crude  petroleum,  however,  it  is  often  incon- 


FIG.  158. — The  Parr  calorimeter  unassembled. 

In  this  type  of  calorimeter  a  carefully  weighed  oil  sample  is  burned  with  a  chemical 
agent  without  the  use  of  free  oxygen.  The  ease  with  which  it  may  be  manipulated  com- 
mends its  use  for  commercial  application.  For  scientific  work,  however,  a  type  of  the  bomb 
calorimeter  is  to  be  preferred. 

venient  to  secure  oxygen  under  the  proper  pressure  required 
for  the  successful  operation  of  this  type  of  calorimeter.     In 


246 


FUEL  OIL  AND  STEAM  ENGINEERING 


recent  years  there  has  appeared  upon  the  market  a  much  simpler 
design  of  calorimeter  which  seems  to  have  sufficient  accuracy  for 
most  commercial  uses  and  is  indeed  quite  simple  in  operation. 
This  is  known  as  the  Parr  calorimeter  and  is  the  invention  of 
Professor  S.  W.  Parr  of  the  University  of  Illinois. 

The  Principle  of  Operation. — In  the  Parr  calorimeter  a  definite 
mass  of  oil  is  introduced  into  a  strong  cylinder  of  metal  called 
the  cartridge,  along  with  some  accelerator  together  with  a 
measure  of  potassium  peroxide.  The  potassium  peroxide 

furnishes  oxygen  for  combustion  and 
the  accelerator,  which  is  usually 
potassium  chloride,  insures  that  all 
the  fuel  may  be  burned.  The  ignition 
is  effected  electrically  by  the  burning 
out  of  a  fine  iron  wire  immersed  in  the 
mixture. 

As  shown  in  the  illustration,  the 
cartridge  D,  in  which  the  sample  is 
placed,  is  closed  up,  inserted  into  a  can 
of  water  A,  and  the  whole  placed  in  a 
fibre  vessel  B,  which  thus  brings  about 
careful  heat  insulation.  After  causing 
an  explosion  by  means  of  an  electrical 
contact  spark  in  the  cartridge  D,  the 
cartridge  is  given  a  rotary  motion  by 
means  of  the  pulley  P  and  the  heat 
which  is  given  out  from  the  cartridge 
due  to  the  burning  of  the  ingredients 
is  rapidly  absorbed  by  the  water  in 

the  vessel  A .  If  then  we  know  the  mass  of  the  sample  burned, 
and  the  mass  and  temperature  of  the  water  before  and  after  the 
explosion,  we  can  compute  the  heat  value  of  the  fuel. 

Detailed  Operation  of  the  Parr  Calorimeter. — Let  us  now  go 
into  the  details  of  this  calorimeter  operation.  A  well  lighted 
closet  should  be  used  for  all  calorimeter  work  so  that  air  currents 
which  might  otherwise  prevent  uniform  radiation  can  thus  be 
eliminated.  The  outside  of  the  calorimeter  cup  and  of  the  fibre 
insulating  case  should  be  entirely  free  from  moisture  for  the 
same  reason.  The  calorimeter  cup  A  is  filled  with  2000  grams  of 
water.  The  cartridge  or  bomb  in  which  the  sample  is  placed 
has  a  water  equivalent  of  135  grams;  that  is,  it  absorbs  the  same 


FIG.     159.  —  Cross-sectional 
view  of  the  Parr  calorimeter. 


DETERMINATION  OF  HEATING  VALUE  OF  OILS       247 

amount  of  heat  as  135  grams  of  water  would  under  the  same  range 
of  temperature.  Hence,  the  total  water  equivalent  We  is  2135 
grams.  As  the  mass  of  oil  is  also  determined  in  grams,  the  water 
equivalent  We  divided  by  the  mass  of  oil  fired,  W0,  becomes  an 
abstract  ratio,  and,  if  this  ratio  is  multiplied  by  the  rise  in  tem- 
perature of  the  water  in  degrees  Fahrenheit,  the  result  is  heat 
units  per  pound  of  oil,  or,  if  the  temperature  is  expressed  in  degrees 
Centigrade,  the  result  becomes  calories  per  gram. 

The  water  is  best  measured  in  a  2000  cc.  flask.  About  2003 
cc.  of  water  are  used  instead  of  an  exact  2000  cc.,  since  the  specific 
gravity  of  water  at  ordinaiy  room  temperatures  is  slightly  less 
than  unity  and  this  increased  volume  is  necessary  to  measure 
weights  volumetrically. 

The  thermometer  which  is  employed  in  temperature  measure- 
ments has  a  range  of  from  65°F.  to  90°F.  and  is  standardized  by 
the  Bureau  of  Standards  at  Washington.  Graduation  errors  are 
known  to  within  0.01°F.  The  thermometer  scale  is  divided  to 
0.05°  and  with  care  may  be  read  to  0.005°.  The  greatest  chance 
for  error  in  fuel  calorimeters  is  in  reading  temperatures,  since  it  is 
difficult  to  avoid  parallax.  Consequently  as  the  rise  in  tempera- 
ture seldom  exceeds  5°,  an  error  of  0.01°  is  equivalent  to  0.2  per 
cent,  error  in  the  work. 

Preliminary  Precautions. — Before  placing  the  sample,  the 
cartridge  should  be  wiped  clean  and  dry,  as  moisture  will  con- 
dense on  it  if  it  has  been  standing  for  some  time.  The  top  and 
bottom  pieces,  as  well  as  the  gaskets  and  electrical  terminals, 
should  be  dry,  since  the  moisture  on  them  takes  part  in  the  chemi- 
cal reaction  and  thus  introduces  considerable  error.  The 
cartridge  should  be  tightly  assembled,  and  1.500  grams  of  accel- 
erator (potassium  chloride),  weighed  to  the  nearest  reading  of 
0.005  grains,  placed  therein.  The  oil  is  weighed  in  a  small  flask 
with  an  eye  dropper  and  about  0.04  to  0.05  grams  (8  to  12  drops) 
dropped  into  the  cartridge  upon  the  accelerator  which  absorbs 
the  oil.  Upon  reweighing  the  flask  of  oil  and  the  dropper,  the 
net  weight  of  the  oil  sample  is  at  once  obtained.  A  measure  full 
of  sodium  peroxide  is  added  and  the  contents  thoroughly  mixed 
with  a  stiff  wire.  With  care  no  oil  and  very  little  peroxide  will 
adhere  to  the  wire.  The  sodium  peroxide  should  be  supplied  by 
the  calorimeter  manufacturer,  as  inferior  grades  are  apt  to  contain 
variable  and  detrimental  products  of  combustion. 

About  3  in.  of  No.  4  iron  wire  for  firing  the  charge  are  next 


248  FUEL  OIL  AND  STEAM  ENGINEERING 

looped  on  the  firing  terminals  and  tested  out  to  insure  a  good 
electrical  contact.  The  firing  current  is  usually  supplied  by  a 
few  dry  cells  or  from  a  storage  battery. 

The  stem  of  the  bomb  is  next  fastened  in  place  and  the  vanes 
attached.  The  cartridge  is  placed  in  the  calorimeter  cup,  the 
cover  and  pulley  attached,  and  the  cartridge  stirred  by  a  small 
motor  for  about  five  minutes.  The  motor  may  be  of  the  toy 
variety  and  is  usually  placed  in  the  lighting  circuit  with  a  lamp 
resistance.  The  electric  circuit  is  controlled  with  a  two-throw 
switch  so  that  the  motor  may  be  cut  in  and  out  without  interfer- 
ing with  the  illumination  in  the  closet.  The  motor  speed  should 
be  as  nearly  constant  as  possible,  since  a  variable  speed  will  cause 
a  variable  rate  of  radiation  from  the  calorimeter.  The  rotating 
bomb  should  have  from  100  to  150  revolutions  per  minute. 

The  Explosion  of  the  Charge  and  the  Taking  of  Temperatures. 
The  thermometer  is  next  placed  into  the  water  bath  through  a 
hole  in  the  cover  and  should  be  supported  so  that  it  does  not 
touch  the  metal  cup  which  contains  the  water.  After  a  steady 
initial  temperature  has  been  reached,  the  firing  circuit  is  com- 
pleted through  the  pulley,  and  the  resulting  temperatures  read 
every  minute  for  the  succeeding  ten  minutes,  in  order  to  ascertain 
the  correction  to  be  made  for  uniform  radiation.  This  series  of 
readings  is  taken  in  order  to  ascertain  the  law  of  radiation  and 
then  to  make  a  proper  correction  for  the  error  involved. 

Thus,  for  a  period  of  about  five  minutes  the  temperature  will 
rise  until  a  maximum  is  reached,  after  which  it  will  begin  to  fall. 
The  radiation  during  the  first  five  minutes  is  assumed  to  be  at 
the  same  rate  as  that  observed  during  the  entire  radiation  period. 
Let  us  assume  the  following  experimental  data: 

Water  equivalent  of  calorimeter 135    grams 

Weight  of  water  used 2000    grams 

Weight  of  oil  used 0 . 3765  grams 

Per  cent,  moisture  in  oil 0.5% 

Weight  of  accelerator 1500  grams 

Room  temperature 70°F. 

Temperature  of  mixture  when  fired,  73.665°F. 

Combustion  Period 

Imin 77.45 

2  min .' 78.15 

3  min 78.42 

4  min 78 . 44 

5  min..  78.45 


DETERMINATION  OF  HEATING  VALUE  OF  OILS        249 

Radiation  Period 

6  min 78.44 

7  min 78.42 

8  min 78 . 40 

9  min 78.385 

10  min..  78.370 


The  Correction  for  Temperature  Readings. — Since  from  the 
above  it  is  seen  that  the  temperature  falls  off  from  its  highest 
reading,  thj  or  78.45°F.  to  78.37°F.  in  five  minutes,  it  is  evident 
that  in  one  minute  it  would  fall  off  0.016°F.  As  a  consequence 
at  the  end  of  the  combustion  period,  in  reality  the  thermometer 
should  have  read  greater  than  fo  or  78.45°F.  by  an  amount  equal 
to  the  radiation  tr  which  is  (0.080)  over  the  first  five  minute  period. 
In  addition  to  this  correction,  by  consulting  a  correction  scale 
furnished  by  the  Bureau  of  Standards,  the  thermometer  should 
be  corrected  for  78.45°F.  by  an  amount  equal  to  tC2  or  (—  0.053°) 
and  for  the  minimum  temperature  tm  or  73.665°F.  equal  to  tcl 
or  (—  0.043°).  From  the  instrument  maker  there  has  also  been 
furnished  data  indicating  a  correction  for  the  chemicals  and  wire 
employed,  amounting  to  tw  or  (—  0.373).  Hence  the  true  maxi- 
mum temperature  1%  and  the  true  minimum  temperature  t\ 
are  ascertained  by  the  formulas: 

t*  =  th  +  tc2  +  tr  +  tw  (3) 

ti    =    tm   +    td  (4) 

Substituting  in  the  particular  case  cited,  we  have 

t2  =  78.450  -      0.053  +  0.080  -  0.373  =  78.104 

*i  =  73.665      -    0.043  =  73.622 

Since  a  careful  comparison  of  this  calorimeter  with  the  most 

accurate  type  of  calorimeter  known  in  the  laboratory  has  shown 

that  the  heating  value  per  pound  of  oil  is  0.73  of  the  total  heat 

liberated,  we  have 

n  7iw 
H  =  -^-\h  -  *i)  (5) 

We  now  have  in  this  instance 
H  =  0.78X2186(78  104)  -78^,  lsjm  ^  per  ^  of 

°-3765  oil  as  fired. 

If  it  is  desired  to  ascertain  the  heating  value  of  this  oil  when 
free  from  moisture,  it  is  only  necessary  to  divide  by  the  percent- 
age of  dry  oil  in  the  fuel.  Thus  if  the  oil  sample  contained  0.50 


250  FUEL  OIL  AND  STEAM  ENGINEERING 

per  cent,  of  moisture  we  find  that  the  heating  value  per  pound 
of  dry  oil  would  be  according  to  this  calorimeter  determination 
18,562  divided  by  0.995  which  is  18,658  B.t.u. 

Higher  and  Lower  Heating  Value. — In  the  operation  of  the 
calorimeter  the  gases  produced  by  the  combustion  of  the  sample 
of  oil  are  cooled  down  to  the  temperature  of  the  water  in  the  calo- 
rimeter. In  the  case  of  carbon  which,  on  igniting  with  oxygen 
produces  CO2,  this  cooling  of  the  gas  has  no  important  effect 
since  CO2  remains  a  gas  at  all  ordinary  temperatures.  Hydrogen, 
on  the  other  hand,  on  uniting  with  oxygen  forms  steam,  H2O, 
which  is  condensed  to  water  in  the  calorimeter  as  soon  as 'its 
temperature  drops  below  212°F.,  and  in  condensing  gives  up  its 
latent  heat  to  the  calorimeter.  When  fuel  oil  is  burned  under  a 
boiler  the  gases  are  always  discharged  at  a  temperature  higher 
than  212°  so  that  the  latent  heat  of  steam  formed  by  the  combus- 
tion of  the  hydrogen  content  is  not  available  and  cannot  be  ab- 
sorbed by  the  boiler.  Hydrogen  combines  with  eight  times  its 
weight  of  oxygen  so  that  for  each  pound  of  hydrogen  burned  9 
Ib.  of  water  are  formed,  and  as  the  latent  heat  of  steam  is 
970  B.t.u.  per  pound,  there  are  approximately  9  X  970  =  8730 
B.t.u.,  which  cannot  be  recovered  unless  the  gases  are  cooled 
below  212°F.  Deducting  this  from  62,000  B.t.u.,  the  heating 
value  of  1  Ib.  of  hydrogen  determined  by  a  calorimeter,  gives 
52,270  B.t.u.,  which  is  called  the  lower  heating  value  of  hydrogen. 

Since  oil  contains  a  considerable  proportion  of  hydrogen  it 
has  a  lower  heating  value  as  well  as  the  ordinary  or  higher  heating 
value.  If  a  sample  of  oil  contains  12  per  cent,  of  hydrogen,  and 
the  higher  heating  value  by  calorimeter  test  is  18,562  B.t.u. 
per  pound,  then  the  lower  heating  value  is  18,652  —  0.12  X  8730  = 
17,515  B.t.u.  per  pound.  In  boiler  testing  work  it  is  the  universal 
custom  to  base  calculations  on  the  higher  heating  value  as  given 
by  the  calorimeter,  but  the  lower  heating  value  is  ordinarily 
used  when  calculating  the  efficiencies  of  gas  engines. 


CHAPTER  XXIX 
THEORY  OF  CHIMNEY  DRAFT 

It  is  a  well  known  fact  that  transference  of  heat  by  convection 
currents  accomplishes  the  freezing  of  lakes  in  the  mountains 
and  the  boiling  of  the  teakettle  in  the  kitchen.  In  the  latter 
instance  it  will  be  recalled  that  the  layer  of  water  along  the  por- 
tion of  the  teakettle  exposed  to  the  heat  application  becomes 
heated  and  expands,  thus  making  its  density 
less  than  the  density  of  the  water  in  the  layer 
above;  consequently  this  lower  water  im- 
mediately travels  to  the  water  surface  to 
make  way  for  the  cooler,  heavier  water 
above.  In  the  succeeding  course  of  events 
this  water  too  becomes  heated,  expands 
and  travels  upward  to  make  way  for  other 
cooler  water  which  in  turn  is  heated  and 
forced  to  the  surface.  This  circulation  or 
transference  of  heat  eventually  raises  the 
temperature  of  the  water  to  such  heights 
that  steam  generation  occurs. 

In  looking  into  the  elementary  theory  of 
chimney  draft  it  is  found  that  exactly  sim- 
ilar Convection  Currents  take  place.  The  considered  as  a  vertical 


rj  force  due 
to  Height  oF  cylinder 


air  or  gas  in  the  chimney  is  raised  to  a  high   &*** 


immersed    in 
temperature  by  the  absorption  of  enormous      The  forces  that  act  under 

....  r    i  •  .    i          ,1        f       -i    •        such    conditions     are     quite 

quantities  of  heat  given  out  by  the  fuel  in  comparable   to   the  forces 

i         .  •  i  j.i       j.  r  •          •  acting   upon   a   cylindrically 

COniDUStlOn     and    Consequently    this    air   ex-    shaped  chimney.    Thedown- 


pands  and  becomes  lighter  in  density  than 

,1  •      •        ,1  i  •,!  TT  *ne  weight  of  the  cylindrical 

the  air  in  the  atmosphere  without.     Hence  column  of  heatedgases  within 

,1-1  •  •  i  ,r  i        ,1         the  stack  are  not  equal  to  the 

thlS     heavier     air     pUSheS     Up     through     the    pressure  of  the  heavy  dense 

,.  j  l      j.u        air    entering   the   boiler   fur- 

grate  or  furnace  entrance   and  expels  the  nace,  so  the  entire  cyiindric- 

heated  air  within  only  to  find  itself  a  few  heated  gaXs  forced  ^pVa^d 

moments   later  also  forced  up  through  the  a 

chimney  by  still  other  heavier  air  without.     And  so  the  process 

continues. 

The  Law  of  Pressures  in  Chimney  Draft.  —  Let  us  consider  a 
volume  of  gas  or  air  housed  up  in  a  chimney  of  area  A  and  height 

251 


252  FUEL  OIL  AND  STEAM  ENGINEERING 

h.  We  may  consider  this  cylinder  of  air  as  immersed  in  a  sea 
of  air  with  its  faces  respectively  hi  and  h2  ft.  below  the  surface. 
This  is  quite  approximately  the  actual  conditions  in  the  air 
surrounding  the  modern  power  plant. 

Let  w  =  weight  of  a  cubic  foot  of  air  without. 

Wi  =  weight  of  a  cubic  foot  of  heated  air  within. 
Let  pi  =  the  unit  pressure  of  atmosphere  at  a. 

Then  evidently  pi  =  wh\ 
Also  pz  =  The  unit  pressure  of  atmosphere  at  b. 

Then  p2  =  wh2 
Hence 

Total  downward  pressure  at  a  =  piA  =  whiA 
Total  upward  pressure  at  b  =  p2A  =  wh2A 
Total  down  pressure  due  to 

weight  of  air  in  chimney 
Total 


Net  upward  press.  =  wh2A  —  whiA  — 
=  wA  (h2  —  hi)  —  WiAh 

But  h2  -  hi  =  h 
.*.  Total  net  upward  press.  =  wAh  — 

Let  W  =  weight  of  a  cylinder  of  outside  air  of  dimensions  of 
chimney  =  w  A  h 

Wi  =  weight  of  a  cylinder  of  inside  air  of  dimensions  of 
chimney  =  Wi  A  h 

.*.  Total  net  upward  pressure  =  W  —  W\    .  (2) 

Hence  the  total  pressure  that  tends  to  force  the  heated  gases 
out  of  a  chimney  is  computed  by  subtracting  the  weight  of  the 
chimney  gases  in  the  chimney  from  the  weight  of  an  outside 
volume  of  air  equal  to  the  volume  of  the  chimney. 

The  Theoretical  Draft.  —  In  thermodynamics,  we  find  that  the 
weight  of  a  so-called  perfect  gas,  in  which  classification  chimney 
gases  are  placed,  may  be  computed  from  the  formula 

pV  =  WRT  (3) 

in  which  p  is  the  pressure  in  pounds  per  square  foot,  V  the  volume 
considered  in  cubic  feet,  W  the  weight  in  pounds,  R  a  constant 
(which  for  air  is  53.3)  and  T  the  absolute  temperature  of  the 
gas  in  degrees  Fahrenheit. 


THEORY  OF  CHIMNEY  DRAFT  253 

Let  us  assume  that  the  pressure  of  the  atmosphere  is  14.7  Ib. 
per  square  inch  or  14.7  X  144  Ib.  per  square  foot,  that  V  is 
unity  or  in  other  words  1  cu.  ft.,  and  that  the  temperature  of 
the  entering  air  is  62°F.  or  on  the  absolute  scale  is  (459.6  +  62)F. 
We  now  have  that  1  cu.  ft.  of  entering  air  weighs 

PV    _  14V0044  X  1  _  0  ,, 

'  RT  '     53.3  X  52L6~ 

The  average  temperature  of  the  outgoing  chimney  gases  is  in 
economic  practice  about  500°F.  or  959.  6°F.  on  the  absolute  scale. 
Hence  a  cubic  foot  of  this  air  will  weigh  on  its  emergence  from 
the  stack 

w      PV       14.7  X  144  X  1 
=          =      53.3X959.6    = 


The  difference  between  0.0761  and  0.0414  is  0.0347  Ib.  If 
now  we  assure  that  the  chimney  stack  is  100  ft.  high  we  find  that 
the  entering  air  forces  itself  inward  with  an  unbalanced  force  of 
3.47  Ib.  over  every  square  foot  of  cross-sectional  area  in  the 
chimney. 

In  engineering  practice  this  draft  pressure  is  not  usually  re- 
corded in  pounds  pressure  per  square  foot  of  chimney  area.  In- 
stead of  this  unit,  the  engineer  measures  the  height  to  which  a 
column  of  water  would  be  forced  under  this  pressure.  In  other 
words,  since  water,  one  square  foot  in  cross-sectional  area,  at 
the  temperature  of  the  boiler  room  usually  weighs  62.0  Ib.,  for 
every  foot  in  height,  to  bring  about  a  pressure  of  3.47  Ib.  per 
square  foot,  the  water  would  have  to  rise  to  a  height  of 

3  47  3  47 

^r—  ft.,  or^Ti  X  12  in.  =  0.67  inches  of  water. 

bz.U  b2.l) 

Hence  it  is  seen  that  under  normal  conditions  of  operation  in 
the  modern  chimney,  the  theoretical  draft  should  read  0.67 
inches  of  water,  when  the  stack  is  100  ft.  high. 

This  theoretical  intensity  of  draft  can  never  be  actually  ob- 
served with  a  draft  gage  or  any  recording  device.  If,  however, 
the  ash  pit  doors  of  the  boiler  are  closed  and  there  is  no  perceptible 
leakage  of  air  through  the  boiler  setting  or  flue,  with  a  stack  100 
ft.  high  filled  with  gases  at  500°F.,  and  with  external  air  at  62°F., 
a  draft  gage  connected  to  the  base  of  the  stack  will  read  approxi- 
mately 0.67  inches. 


254  FUEL  OIL  AND  STEAM  ENGINEERING 

DRAFT  FORMULA  FOR  THE  MODERN  POWER  PLANT 

Assuming  that  the  density  of  the  chimney  gas  is  the  same  as  air 
under  the  same  conditions  of  pressure  and  temperature,  we  can 
at  once  by  following  the  simple  numerical  illustration  given  in  the 
last  discussion  develop  a  formula  not  only  for  a  chimney  100  ft. 
in  height,  but  for  any  height  H  and  absolute  temperature  T  of 
entering  air  and  absolute  temperature  TI  of  stack  gases. 

By  substituting  in  the  elementary  formula  for  chimney  gases 
connecting  pressures,  volumes,  and  absolute  temperature  as  set 
forth  in  the  last  discussion  we  have,  where  Wi  is  the  total  weight 
of  air  within  the  chimney  and  W  the  weight  of  an  equal  volume  of 
air  without  the  chimney  that 


Hence  the  net  force  pressing  inward  from  the  outside  heavier 
air  over  the  entire  chimney  area  A  sq.  ft.  is 
Net  force  in  Ib.  = 

w-  W  =$v,.pL  =  pV(l-  JL\ 

RT      RTl  "   R  \T       Tj 

If  the  height  of  the  chimney  is  H  ft.  and  its  area  of  cross-section 
A  sq.  ft.  we  have,  since  V  =  AH, 


AT    ^  r  -it,  PAH  fl  1  \ 

Net  force  in  Ib.  =    ^-  (^  -  ^J 


Then  the  net  force  F  over  one  sq.  in.  of  chimney  cross-section 
would  be  TTT"7  of  the  above,  which  is 

F      J_^pAHi\        l\        pH  /I       1\ 
144A  *      R    \T       TJ      144#  \T     fl  I 

Since  p  is  the  atmospheric  pressure  in  Ib.  per  sq.  ft.,  we  have 
that  p  =  144P,  wherein  P  is  the  atmospheric  pressure  in  Ib.  per 
sq.  in.,  and  also,  since  R  =  53.3  we  have 

144ffP     / 1       JA        HP /I        l\ 
144  X  53.3  \T      Tj      53.3  \T      Tj 

Converting  F  from  pounds  pressure  per  sq.  in.  to  inches  of 
water  by  substituting  the  weight  of  water  at  the  boiler  room 
temperature  which  is  62.0  pounds  per  cubic  foot,  we  proceed 
exactly  as  in  the  numerical  example  of  the  last  discussion  and 
find  that 

(i) 


THEORY  OF  CHIMNEY  DRAFT 


255 


By  means  of  this  formula,  we  are  enabled  to  compute  drafts  for 
any  temperatures  and  pressures.  Thus  a  chimney  situated 
10,000  ft.  above  sea-level,  where  the  atmospheric  pressure  is 
10  Ib.  per  sq.  in.  with  a  stack  of  100  ft.,  and  entrance  and  exit 
temperature  of  62°F.  and  500°K  respectively,  would  have  a 
draft  of 

D  =  0.52  X  100  X  1 
=  0.46  in.  of  water. 


FIG.   161. — The  theoretical  chimney  draft. 

A  stack  100  feet  high  situated  10,000  feet  above  sea  level,  with  entering  air  at  62°F.  and 
exit  gases  at  500°F.  with  ash  pit  door  closed  and  no  perceptible  leakage  through  the  boiler 
setting,  should  register  0.46  inches  of  draft. 

It  is  seen  that  altitude  has  much  to  do  with  chimney  drafts, 
for  this  identical  chimney  was  previously  shown  to  have  a  draft  of 
0.67  inches  of  water  at  sea  level. 

The  above  formula  gives  the  theoretical  draft — that  is;  the 
draft  that  would  be  obtained  under  perfect  conditions  if  there 
were  no  losses.  In  practice,  however,  there  is  a  considerable  reduc- 
tion in  draft  on  account  of  the  friction  of  the  gases  passing  up 
through  the  stack.  The  greater  the  velocity  of  the  gases,  the 
greater  is  the  friction.  By  increasing  the  diameter  of  the  chim- 
ney for  the  same  capacity  the  velocity  of  gases  is  reduced,  and 
it  is  evident,  therefore,  that  the  diameter  of  the  chimney  has  an 
important  bearing  on  the  net  effective  draft  obtained  at  its 
base. 

The  friction  of  the  gases  passing  up  the  chimney  can  best  be 
calculated  by  means  of  formulse  based  on  the  flow  of  water 


256  FUEL  OIL  AND  STEAM  ENGINEERING 

through  pipes,  for  the  chimney  can  be  considered  to  be  a  vertical 
pipe  with  an  upward  stream  of  gases  flowing  through  it.  Geb- 
hardt1  gives  the  following  formula  based  on  Chezy's  formula  for 
hydraulic  flow: 


where  Dc  =  draft  loss  in  the  chimney,  in.  of  water 
W  =  weight  of  flue  gas,  Ib.  per  sec. 
H  =  height  of  chimney,  feet 

Ti  =  absolute  temperature  of  chimney  gases,  deg.  F. 
d    =  diameter  of  chimney,  inches. 

The  constant  k  is  given  by  different  writers  varying  from  1.6  to 
3.0,  depending  on  the  assumed  coefficient  of  friction  of  the  gases 
against  the  walls  of  the  stack.  For  practical  purposes  it  is  suf- 
ficiently accurate  to  take  the  mean  of  the  above  values,  giving 
the  value  k  =  2.3. 
The  formula,  therefore,  becomes: 


D,  =  2.3  (2) 

Deducting  the  draft  loss  in  the  chimney  from  the  theoretical 
draft,  we  have  the  available  draft,  Di,  at  the  base  of  the  chimney 


(3) 

Expressed  in  words  this  formula  means:  to  find  the  available 
draft  at  the  base  of  the  chimney,  first  calculate  the  theoretical 
draft  by  means  of  formula  (1),  and  then  deduct  the  friction  loss  as 
determined  from  formula  (2)  .  For  example,  let  us  determine  the 
available  draft  at  the  base  of  a  chimney  5  ft.  diameter  and  100  ft. 
high  when  operating  at  sea  level  and  passing  20  Ibs.  of  flue  gas 
per  second  at  a  temperature  of  500°F. 

From  Formula  (1)  we  find,  as  in  the  previous  example,  that 
the  theoretical  draft  is  0.67  inches  of  water.  From  formula  (2)  we 
find  that  the  draft  loss  in  the  chimney 

202  X  100  X  (500  X  461) 
Dc  =  2.3  X—  Q5  -  =  0.11  in.  of  water. 

The  available  draft  at  the  base  of  the  chimney  is  therefore  0.67 
-  0.11   =  0.56  in.  of  water. 
1  Steam  Power  Plant  Engineering  —  Geo.  F.  Gebhardt  —  5th  Ed.,  p.  289, 


THEORY  OF   CHIMNEY  DRAFT 


257 


In  the  table  in  Fig.  162  the  available  draft  is  given  for  chim- 
neys of  various  diameters  all  100  ft.  high,  with  given  quantities 
of  flue  gas  passing  per  hour  based  on  a  temperature  of  gases  of 
500°F.  For  any  other  height  of  chimney  the  draft  may  be  ob- 
tained directly  from  the  table  by  simply  multiplying  the  draft 
given  in  the  table  by  the  actual  height,  and  dividing  by  100. 

DRAFT  PRODUCED  BY  CHIMNEY  100  FEET  HIGH  IN  INCHES  OF  WATER 
Average  Temperature  of  Chimney  Gases,  500°F. 


Diameter  of  rhimnev  in  inches 


Flue  ga 


per  hour. 
Ib. 

36 

42 

48 

54 

60 

66 

72 

78 

84 

90 

96 

102 

108 

114 

120 

132 

144 

156 

168 

180 

20,000 

.65 

.62 

30,000 

.42 

.55 

.60 

40000 

.21 

.46 

.56 

.61 

, 

50,000 

.34 

.49 

.57 

.61 

60,000 

.  19 

.42 

.53 

.59 

.61 

.63 

80,000 

.23 

.43 

.53 

.58 

.61 

.63 

100,000 

.29 

.45 

.53 

.58 

.61, 

.63 

.64 

120,000 

.35 

.47 

.54 

.58 

.61 

.63 

.64 

.65 

160,000 

.31 

.43 

.52 

.56 

.59 

.62 

.63 

.64 

.65 

.65 

200,000 

.30 

.43 

.50 

.55 

.59 

.61 

.62 

.63 

.64 

.65 

250,000 

.30 

.41 

.49 

.54 

.57 

.60 

.61 

.63 

.64 

.65 

300,000 

31 

.41 

.48 

.52 

.56 

.59 

.61 

.63 

.64 

.65 

350,000 

40 

.47 

.52 

.56 

.58 

.62 

.63 

.65 

.65 

.66 

400,000 

.42 

.48 

.52 

.56 

.60 

.62 

.64 

.65 

.66 

450,000 

.43 

.49 

.53 

.58 

.61 

.63 

.64 

.65 

500,000 

44 

.49 

.56 

.60 

.62 

.64 

.65 

550,000 

j 

39 

.45 

.53 

.58 

.61 

.63 

.64 

600,000 

.41 

.50 

.57 

60 

.62 

.63 

Figures  underlined  represent  draft  for  chimney  of  least  first  cost. 

For  other  heights  multiply  the  draft  given  in  the  table  by  the  height  above  the  point  at 
which  the  draft  is  to  be  determined,  and  divide  by  100. 

FlG.   162. 

The  set  of  curves  in  the  diagram  in  Fig.  163  gives  the  same  in- 
formation, with  the  addition  of  extra  scales  which  enable  the 
draft  to  be  determined  for  temperatures  of  300°F.  and  700°F., 
as  well  as  500°F.  By  interpolating  between  the  results  so  ob- 
tained, the  draft  may  be  quickly  determined  for  any  tempera- 
ture between  these  limits. 

This  table  and  diagram  may  be  used  for  determining  the  height 
and  diameter  of  chimney  required  for  any  boiler  plant,  to  produce 
a  given  amount  of  draft,  regardless  of  the  kind  of  fuel  used,  pro- 

17 


258 


FUEL  OIL  AND  STEAM  ENGINEERING 


vided  the  quantity  of  flue  gas  passing  per  hour  can  be  approxi- 
mately estimated. 

The  weight  of  flue  gas  passing  per  second  or  per  hour  depends, 
for  practical  purposes,  on  just  two  things: 

(1)  The  weight  of  fuel  burned. 

(2)  The  per  cent,  excess  air  used  in  burning  it. 


FIG.  163. — Diagram  showing  available  draft  at  chimney  base  for  various  rates 
of  gas  flow  and  chimney  diameters. 

Other  influences,  such  as  moisture  or  oxygen  in  the  fuel,  or 
steam  used  to  atomize  oil,  may  be  neglected,  as  their  effect  is 
small. 

The  weight  of  oil  burned  under  a  boiler,  operating  at  70  per 
cent,  efficiency,  amounts  to  2%  Ib.  per  hour  per  blr.  h.p.  As 
this  efficiency  is  easily  obtained  with  ordinary  care,  this  is  a 
liberal  figure  to  use  for  design  purposes. 


THEORY  OF  CHIMNEY  DRAFT  259 

Oil  can  be  burned  with  no  more  than  15  per  cent,  excess  air, 
corresponding  to  14  per  cent.  CO2,  but  as  extreme  care  is  required 
to  attain  this  result  the  chimney  should  be  designed  on  a  more 
liberal  basis.  A  safe  figure  to  use  is  50  per  cent,  excess  air,  cor- 
responding to  10  per  cent.  CO2.  The  theoretical  amount  of  air 
required  runs  from  13  to  14  Ib.  per  pound  of  oil,  depending  on 
the  chemical  constituents  of  the  oil.  Taking  14  Ib.  as  the  theo- 
retical amount  of  air,  and  adding  50  per  cent,  excess,  we  have  a 
total  of  21  Ib.  of  air  for  each  pound  of  oil,  and  as  the  pound  of 
oil  is  completely  gasified,  there  are  22  Ib.  of  flue  gas  per  pound  of 
oil.  Multiplying  this  by  the  2%  Ib.  of  oil  per  h.p.  gives  58.7, 
or  approximately  60  Ib.  of  flue  gas  per  hour  per  boiler  h.p.  Con- 
sequently the  weight  of  flue  gas  per  hour  passing  up  a  chimney 
may  be  estimated  by  multiplying  the  actual  boiler  horsepower  by 
60. 

In  practice  it  is  customary  to  overload  boilers  up  to  150  per 
cent.,  200  per  cent,  and  sometimes  as  high  as  300  per  cent,  of 
their  rated  capacity.  The  actual  horsepower  may,  therefore,  be 
very  different  from  the  installed  capacity.  In  designing  the 
chimney  it  is  essential  to  know  what  capacity  is  expected  from 
the  boilers,  and  be  guided  accordingly. 

An  Example  of  Chimney  Design  for  Sea-level  Installation. 
Let  us  from  this  data  ascertain  the  diameter  of  a  100-ft.  chimney 
capable  of  properly  creating  a  draft  for  a  1000  h.p.  boiler  instal- 
lation so  that  the  stack  is  of  sufficient  size  to  accommodate  a 
50  per  cent,  overload.  It  is  assumed  that  the  stack  is  centrally 
located  and  that  it  has  short  flue  connections  with  ordinary  operat- 
ing boiler  efficiency  and  that  a  draft  of  0.5  in.  at  the  base  of  the 
chimney  is  sufficient.  Since  the  1000  h.p.  boilers  are  to  operate 
at  50  per  cent,  overload,  the  actual  horsepower  will  be  1500. 
Multiplying  this  by  60  gives  90,000  Ib.  of  flue  gas  per  hour. 
From  the  diagram  it  is  seen  at  a  glance  that  the  chimney  must  be 
a  little  more  than  60  inches  in  diameter  to  give  the  required 
draft  of  0.5  in.  with  gases  at  an  average  temperature  of  500°F. 

It  will  be  noted  from  the  table  that  it  is  possible  to  get  several 
different  combinations  of  heights  and  diameters  of  stacks,  to 
produce  a  given  draft  for  any  particular  weight  of  flue  gas  con- 
sidered. For  instance  the  diagram  shows  that  a  stack  54  in. 
diameter  and  100  ft.  high  will  give  a  draft  of  0.36  in.  when  passing 
90,000  Ib.  of  flue  gas  per  hour  at  a  temperature  of  500°F.  If  the 
height  of  this  stack  is  increased  to  140  ft.,  the  draft  obtained  would 


260 


FUEL  OIL  AND  STEAM  ENGINEERING 


be  0.36  X  14%oo  =  0.50  in.,  which  is  the  same  draft  for  which  the 
60  in.  X  100  ft.  stack  was  figured  in  the  previous  example.  A 
number  of  other  combinations  of  height  and  diameter  can  be  made 
that  will  give  the  same  draft.  The  choice  of  the  actual  chimney 
to  be  used  must  therefore  depend  on  other  considerations  be- 
sides the  draft  and  in  practice  this  point  is  settled  by  selecting 
the  chimney  that  will  be  the  cheapest  to  build.  The  cost  of  a 


FIG.  164. — Typical  sea-level  installation  in  metallic  chimney  design  for  fuel 
oil  practice.  The  view  shown  is  that  of  the  steam  power  plant  auxiliary  for  the 
city  of  Seattle,  Eastlake  and  Nelson  Place. 

chimney  is  roughly  proportioned  to  its  height  times  its  diameter, 
and  on  this  basis  it  has  been  found  that  the  most  economical 
chimney  to  build,  for  a  given  set  of  conditions,  is  that  in  which  the 
available  draft  is  equal  to  eight-tenths  of  the  theoretical  draft. 
In  the  diagram  in  Fig.  163  this  relationship  is  indicated  by  the 
vertical  dotted  line,  and  the  proper  diameter  of  stack  is  found  at  a 
glance  by  noting  the  point  at  which  the  diameter  curves  cross  this 


THEORY  OF  CHIMNEY  DRAFT 


261 


line.  For  example,  considering  once  more  the  case  of  1000  h.p. 
oil-fired  boilers  operating  at  50  per  cent,  overload,  and  requiring 
0.5  in.  draft  at  the  chimney  base,  we  have,  as  before,  90,000  Ib. 
of  flue  gas  per  hour  at  a  temperature  of  500°F.  Following  the 
horizontal  line  corresponding  to  90,000  Ib.  per  hour,  until  it 
crosses  the  vertical  dotted  line,  we 
find  that  the  cheapest  chimney  to 
build  for  this  capacity  will  be  be- 
tween 60  in.  and  66  in.  diameter. 
It  is  customary  to  build  stacks  with 
diameters  equal  to  some  multiple  of 
6  in.  We  may  therefore  select  66  in. 
as  the  required  diameter.  The  dia- 
gram shows  that  under  the  assumed 
conditions  the  draft  for  a  66-in. 
stack,  100  ft.  high,  will  be  0.555  in. 
Since  the  draft  required  is  only  0.5 
in.,  the  height  of  the  stack  may  be 
reduced  in  proportion,  making  it  90 
ft.  high  instead  of  100  ft.  It  is 
thus  found  that  the  proper  size  of 
chimney  for  the  conditions  of  the 
problem  is  66  in.  diameter  and  90 
ft.  high. 

In  the  table  in  Fig.  162  the  chim- 
ney of  least  first  cost  is  indicated  by 
printing  in  bold  type  the  draft  ob- 
tained from  the  proper  size  of  chim- 
ney for  .each  given  capacity. 

Sometimes  stacks  must  be  built 
higher    than    would    otherwise    be 
necessary,  in  order  to  discharge  well 
above     surrounding     buildings,    in 
which  case  a  smaller  diameter  may 
be  used  than  would  be  required  for 
a  lower  stack.     In  tall  office  build- 
ings the  height  of  the  stack  is  determined  by  the  height  of  the 
building  itself.    It  is  not  generally  known  that  the  tallest  chimney 
in  the  world  is  the  one  provided  for  the  power  plant  of  the 
Woolworth  Building  in  New  York. 

Chimneys  that  have  small  diameters  in  proportion  to  their 


FIG.  165. — The  power  plant  in 
the  Woolworth  Building,  New 
York,  has  the  tallest  chimney  in 
the  world.  The  height  of  the 
stack  is  determined  by  that  of 
the  building,  but  in  some  cases 
the  stack  must  be  built  extra 
high  in  order  to  discharge  well 
above  surrounding  buildings. 


262 


FUEL  OIL  AND  STEAM  ENGINEERING 


height  are  somewhat  objectionable  on  account  of  the  variability 
of  the  draft.  At  the  full  load  of  1000  boiler  h.p.,  as  we  have  seen, 
a  54  in.  X  140  ft.  stack  gives  the  same  draft  as  a  66  in.  X  90  ft. 
stack.  At  light  loads,  however,  the  54  in.  X  140  ft.  stack  will 
give  a  much  greater  draft,  for  it  still  has  its  full  height,  but  the 
friction  loss  is  much  less.  This  increase  of  draft  at  light  loads 
requires  special  care  on  the  part  of  the  boiler  fireman  to  adjust  his 
dampers  for  proper  air  regulation. 

Corrections  in  Chimney  Height  for  Altitude. — We  shall  next 
consider  the  necessary  corrections  to  be 
made  in  the  dimensions  of  proposed  chim- 
neys in  their  relation  to  altitude  above  the 
sea.  All  chimney  dimensions  and  tables 
have  been  computed  on  the  basis  of  sea- 
level  pressures.  From  our  equation  of 
draft  readings  previously  derived,  it  is  seen 
that  the  draft  depends  directly  upon  the 
atmospheric  pressure.  Hence  it  is  evident 
that  since  the  higher  the  altitude,  the  less 
the  pressure,  the  stack  must  be  lengthened 
in  proportion  to  the  barometric  readings. 
Thus  if  H  is  the  proper  height  of  a  chim- 
ney at  sea  level  or  barometric  pressure  P0, 
then  HI  the  proper  height  at  the  altitude 
PI  above  sea  level  is  as  follows: 


H       Pl 

or  if  r  is  a  factor  obtained  by  dividing  the 
barometric  reading  at  sea  level  by  the 
barometric  reading  at  the  proposed  point 
of  installation, 


FIG.  166.  — Atmos- 
pheric barometer. 


Hi  =  rH 


This  reasoning  is  based  on  the  assumption  of  constant  draft 
measured  in  inches  of  water  at  the  base  of  the  stack  for  a  given 
rate  of  operation  of  the  boilers  regardless  of  altitude. 

An  important  point  to  consider  in  the  construction  of  the  stack 
is  how  the  altitude  will  affect  the  cross-sectional  area.  At  high 
altitudes  the  air  becomes  less  dense,  hence  the  area  should  be 
larger  in  order  to  pass  the  required  weight  of  air  needed  in  com- 


THEORY  OF  CHIMNEY  DRAFT  263 

bustion  of  the  fuel,  for  the  same  weight  of  air  is  needed  for  proper 
fuel  combustion,  no  matter  what  the  altitude  may  be. 

In  the  flow  of  gases  through  pipes,  it  has  been  found  that  the 
weight  passing  any  given  section  per  minute  is 

M 


Where  K  is  constant;  p  is  the  difference  in  pressure  between  two 
ends  of  pipe;  D  the  density;  d  the  diameter  of  pipe  in  inches;  and 
L  the  length  of  pipe.  Since  these  quantities  will  later  disappear 
in  self-cancelling  pairs  from  this  equation,  the  noting  of  the  par- 
ticular units  involved  in  measurement  is  not  necessary.  In 
applying  this  formula  to  gases  flowing  through  a  stack,  the  quan- 
tity (in — -y-j  is  practically  unity,  the  quantity  L  becomes  equal 

to  H  and  Hi  in  the  respective  cases,  and  p  is  the  same  in  each  case. 
Hence  we  have 

W  -  K 


But  W  must  equal  Wi  for  the  same  economy  of  fuel  burning. 
Hence 


Also 


D  .Hi 

--rand-gr-r 


Therefore,  substituting  and  cancelling 
Dd*        Didi* 

H          #T 
r_D^_  =DidS 

H  rH 

r2r/5  =  rfls  ,\di  =  drH 

Rule  for  Altitude  Correction. — Hence  to  properly  proportion 
a  chimney  for  a  given  altitude  above  sea  level,  first  pick  the  height 
and  diameter  for  the  boiler  capacity  on  the  assumption  that  the 
installation  is  to  be  made  at  sea  level.  Next  determine  the  height 
for  the  altitude  desired  by  making  the  ratio  of  the  new  height  to 
the  sea-level  determination  inversely  proportional  to  the  baro- 
metric readings.  The  stack  diameter  is  then  increased  so  that 


264  FUEL  OIL  AND  STEAM  ENGINEERING 

the  stack  at  the  higher  altitude  should  have  the  same  frictional 
resistance  as  that  used  at  sea-level.  This  new  diameter  is  de- 
termined by  multiplying  the  diameter  obtained  on  the  basis  of 
sea-level  assumption  by  the  ratio  r  of  barometric  heights  raised 
to  the%th  power  as  above  deduced. 

An  Example  of  Chimney  Design  at  Altitude/ — Since  it  is  now 
seen  that  the  factor  or  ratio  of  sea-level  pressure  to  the  pressure 
at  altitude  enters  as  a  first  and  a  two-fifths  power,  a  chart  is 
herewith  given  by  means  of  which  this  factor  may  be  quickly 
raised  to  the  power  desired  for  altitudes  up  to  10,000  ft.,  without 
any  reference  to  barometric  pressures. 

As  an  example,  let  us  find  the  proper  proportions  of  a  chimney 
to  amply  provide  for  a  1000  boiler  horsepower  installation  situ- 
ated 8000  ft.  above  sea-level. 

We  have  hitherto  found  that  the  proper  dimensions  at  sea- 
level  for  such  an  installation  are  66  in.  in  diameter  for  a  height  of 
90  ft.  Applying  our  rule  set  forth  above,  we  find  from  the  chart 
that  r  for  8000  ft.  is  1.357.  Hence  the  proper  height  is  122  ft. 
at  this  altitude,  and  since  r  raised  to  the  %th  power  is  found  from 
the  chart  to  be  1.130  the  proper  diameter  is  74.5  in. 


CHAPTER  XXX 
ACTUAL  DRAFT  REQUIRED  FOR  FUEL  OIL 

For  every  kind  of  fuel  and  rate  of  combustion  there  is  a  certain 
draft  with  which  the  best  general  results  are  obtained.  A 
comparatively  light  draft  is  best  for  burning  bituminous  coals 
and  the  amount  to  use  increases  as  the  percentage  of  volatile 
matter  diminishes  and  the  fixed  carbon  increases,  being  highest 
for  the  small  sizes  of  anthracites.  Numerous  other  factors  such 
as  the  thickness  of  fires,  the  percentage  of  ash  and  the  air  spaces 
in  the  grates  bear  directly  on  this  question  of  the  draft  best 
suited  to  a  given  combustion  rate. 

For  fuel  oil,  the  question  of  draft  required  is  greatly  simplified 
by  the  fact  that  the  air  does  not  have  to  be  drawn  in  through  a 
thick  bed  of  fuel  and  there  are  no  ashes  or  clinkers  to  further 
complicate  the  matter.  The  resistance  offered  to  the  entrance 
of  air  to  the  furnace  is  caused  by  the  checkerwork  furnace  floor, 
and  as  the  openings  in  the  checkerwork  can  be  altered  at  will,  it  is 
evident  that  the  amount  of  draft  required  in  the  furnace  will 
depend  largely  on  the  arrangement  of  checkerwork  adopted. 

For  a  furnace  arrangement  such  as  shown  on  page  158,  in 
which  the  total  net  area  of  free  air  space  amounts  to  3  to  3J£  sq. 
in.  per  rated  horsepower  of  the  boiler,  the  draft  required  in  the 
furnace  amounts  to  the  following,  approximately: 

Per  cent,  of  rating  Draft  in  furnace, 

inches  of  water 

100  0.05 

150  0.10 

200  0.25 

The  draft  in  the  furnace  is  only  a  small  proportion  of  the  total 
draft  that  must  be  supplied  by  the  chimney,  for  it  is  necessary 
to  add  to  the  furnace  draft  the  draft  loss  caused  by  the  friction 
of  the  gases  in  passing  through  the  boilers,  breechings  and  flues 
leading  to  the  chimney. 

265 


266  FUEL  OIL  AND  STEAM  ENGINEERING 

DRAFT  LOSSES  IN  STEAM  POWER  GENERATION 

The  loss  of  draft  is  greatest  in  boilers  having  the  longest  path 
of  gases,  the  greatest  velocity,  and  the  greatest  number  of  changes 
in  direction  of  flow  of  gases.  A  boiler  having  a  single  pass  with 
the  hot  gases  entering  at  the  bottom  and  leaving  at  the  top  has  a 
minimum  draft  loss.  In  most  designs  of  boilers,  however,  this 
arrangement  cannot  be  adopted  as  the  area  of  gas  passage  would 
be  too  large.  This  would  result  in  the  gases  short  circuiting, 
that  is  passing  in  a  narrow  stream  from  one  corner  to  the  other 
without  coming  in  contact  with  all  of  the  heating  surface.  To 
make  the  heating  surface  effective  in  absorbing  heat  from  the 
gases  it  is  therefore  necessary  to  provide  baffles  in  the  boiler, 
which  deflect  the  gases  and  cause  them  to  travel  back  and  forth 
until  their  temperature  has  been  reduced  as  much  as  possible. 

The  arrangement  of  baffles  is  a  feature  of  boiler  design  and  need 
not  be  entered  into  here.  It  is  well,  however,  to  refer  briefly 
to  the  general  principle  involved,  namely,  that  the  higher  the 
velocity  of  gases  traveling  over  the  heating  surface  the  greater 
will  be  the  coefficient  of  heat  transfer.  Consequently  it  would 
seem  that  in  order  to  insure  maximum  efficiency  of  the  boiler 
there  should  be  a  large  number  of  passages  of  small  area,  so  as 
to  insure  high  velocity  to  the  gases.  This  is  true  up  to  certain 
limits,  but  unfortunately  it  is  soon  found  that  the  additional  loss 
of  draft  caused  by  increased  friction  and  extra  changes  in  direc- 
tion of  the  gases  makes  the  production  of  the  required  draft 
both  difficult  and  expensive. 

In  the  majority  of  water  tube  boilers  the  baffles  are  arranged 
for  three  passes,  that  is  the  gases  are  forced  to  travel  the  length 
or  height  of  the  boiler  setting  three  times  before  reaching  the 
stack.  With  this  arrangement  the  areas  of  passes  are  such  as  to 
give  the  gases  a  velocity  of  10  or  15  ft.  per  second  when  the  boiler 
is  operating  at  its  rated  capacity.  By  increasing  the  number  of 
passes  to  four  or  five  the  velocity  may  be  increased  to  20  or  30 
ft.  per  second.  This  results  in  a  higher  rate  of  heat  transmission 
so  that  more  heat  is  absorbed  from  the  gases,  reducing  their 
temperature  and  resulting  in  less  waste  to  the  chimney. 

To  enable  the  number  of  passes  in  a  boiler  to  be  increased  the 
chimney  must  be  designed  to  suit  the  increased  loss  of  draft  that 
will  occur.  Thus  in  every  case  the  actual  draft  loss  should  be 
determined  as  closely  as  possible,  and  the  actual  figures  for  the 


ACTUAL  DRAFT  REQUIRED  FOR  FUEL  OIL  267 

particular  case  in  hand  used  in  designing  the  chimney.  It  is 
desirable  in  all  cases  to  design  the  stack  for  a  greater  draft  than 
is  expected,  for  it  is  a  simple  matter  to  reduce  the  draft  by  closing 
in  on  the  damper,  whereas  if  the  draft  is  insufficient  nothing  can 
be  done  to  increase  it.  Again,  it  may  be  desired  at  some  future 
time  to  increase  the  number  of  passes  in  the  boiler,  or  otherwise 
modify  the  baffles  in  such  a  way  as  to  require  more  draft.  This 
would  be  impracticable  unless  the  stack  is  large  enough  to  pro- 
duce a  surplus  of  draft. 

In  order  to  give  the  reader  some  general  ideas  of  computations 
involved  in  ascertaining  draft  losses  assumed  in  design  we  shall 
now  pass  to  a  brief  consideration  of  this  problem. 

Loss  of  Draft  in  Boilers. — The  loss  of  draft  through  a  boiler 
proper  will  depend  upon  its  type  and  baffling,  and  will  increase 
with  the  per  cent,  of  rating  at  which  it  is  run.  For  design  pur- 
poses, it  may  be  assumed  that  the  loss  through  an  oil  fired  boiler 
between  the  furnace  and  the  damper  will  be  0.15  in.  when  it  is 
run  at  its  rating,  0.35  in.  at  150  per  cent,  of  its  rating  and  0.60 
in.  at  200  per  cent,  of  its  rating. 

Loss  in  Flues  and  Turns. — With  circular  steel  flues  of  approxi- 
mately the  same  size  as  the  stack  or  when  reduced  proportion- 
ally to  the  volume  of  gases  they  are  to  handle,  a  convenient  rule 
is  to  allow  0.1  in.  draft  loss  per  100  ft.  of  flue  length  and  0.05  in 
for  each  right  angle  turn.  These  figures  are  also  good  for  square 
or  rectangular  steel  flues  with  areas  sufficiently  large  to  provide 
against  excessive  frictional  loss.  For  losses  in  brick  or  concrete 
flues  these  figures  should  be  doubled. 

Thus  the  loss  in  draft  flues  and  turns  for  an  installation  having 
a  flue  100  ft.  long  and  containing  two  right  angle  turns  is 

Loss  for  flues,  per  100  ft.  0.1  in. 

Turns  2  X  0.05  0.1  in. 

0.2  in.  loss 

Total  Available  Draft  Required. — We  are  now  enabled  to 
compute  the  total  available  draft  required  for  a  boiler  installation 
by  summing  up  the  separate  components  required  for  the  fur- 
nace, for  the  boiler,  for  the  flues  and  for  the  turns. 

Thus,  for  an  oil  fired  boiler  to  operate  at  200  per  cent,  of  its 
rated  capacity,  connected  to  a  chimney  through  a  flue  100  ft. 


268  FUEL  OIL  AND  STEAM  ENGINEERING 

long  and  containing  two  right  angle  turns,  we  have  the 
following : 

Draft  in  furnace 0 . 25  in. 

Draft  loss  in  boiler 0 . 60  in. 

Draft  loss  in  flue 0 . 20  in. 

Draft  required  at  base  of  chimney 1 . 05  in. 

The  size  of  chimney  required  to  produce  this  draft  may  be 
determined  by  the  method  described  in  the  last  chapter.  Thus, 
let  us  suppose  we  are  considering  an  installation  of  2500  h.p. 
At  200  per  cent,  of  rating  there  will  be  5000  h.p.  actually  devel- 
oped, and  the  quantity  of  flue  gas  produced  by  the  oil  fires  will 
be  5000  X  60  =  300,000  Ib.  per  hour.  From  the  diagram  on 
page  258  we  find  that  a  chimney  for  this  capacity  should  be 
102  in.  diameter.  We  may  assume  that  at  the  capacity  con- 
sidered the  average  temperature  of  chimney  gases  will  be  600°F. 
The  diagram  on  page  258  gives  the  draft  for  a  chimney  102  in. 
diameter  and  100  ft.  high  with  300,000  Ib.  per  hour  of  flue  gas, 
0.525  in.  for  500°F.,  and  0.63  in.  for  700°F.  Interpolating  we 
have  a  draft  of  0.58  in.  for  a  temperature  of  600°F.  Since  the 
draft  required  is  1.05  in.,  the  height  of  the  chimney  must  be 

100  X  (pgg  =  181  ft.     This  is  the  height  of  the  chimney  above 

t'he  point  at  which  the  flue  enters.  If  the  flue  enters  the  chimney 
14  ft.  above  the  ground,  then  the  total  height  of  the  chimney 
must  be  195  ft. 

Artificial  Draft. — As  we  have  seen  draft  in  a  stack  is  caused 
by  difference  in  pressure  between  the  gases  inside  and  outside, 
resulting  in  a  flow  of  air  from  the  higher  external  pressure  to  the 
lower  internal  pressure.  A  similar  difference  in  pressure,  and 
consequent  flow  of  air,  may  be  produced  by  a  fan  or  blower  in- 
stead of  by  a  chimney.  When  this  is  done  we  have  what  is 
known  as  Artificial  Draft. 

There  are  two  forms  of  artificial  draft  known  as  Forced  Draft 
and  Induced  Draft,  the  distinguishing  feature  between  the  two 
being  the  location  of  the  fan  in  respect  to  the  boiler. 

In  the  case  of  Forced  Draft  the  fan  sucks  air  direct  from  the 
atmosphere  and  delivers  it  to  the  boiler,  under  pressure  somewhat 
greater  than  that  of  the  atmosphere.  In  the  case  of  Induced 
Draft  the  fan  is  located  between  the  boiler  and  the  stack,  sucks 
the  gases  of  combustion  out  of  the  boiler  and  discharges  them  to 
the  stack. 


ACTUAL  DRAFT  REQUIRED  FOR  FUEL  OIL  269 

Since  Forced  Draft  produces  a  pressure  greater  than  atmos- 
pheric, its  use  is  confined  principally  to  forcing  air  through  a 
thick  bed  of  fuel  on  the  grates.  It  is  used  largely  in  connection 
with  certain  kinds  of  stokers,  and  frequently  with  hand  fired 
boilers  using  low  grade  coals.  Forced  draft  is  not  suitable  for 
steam  atomized  oil  fired  boilers,  because  there  being  no  fuel  bed 
on  the  grates  to  offer  resistance,  the  positive  pressure  from  the 
fan  discharge  would  be  carried  up  into  the  boiler  setting.  This 
would  cause  the  gases  to  leak  out  into  the  boiler  room,  and  in 
some  cases  would  result  in  excessive  furnace  temperature  and 


FIG.    167. — Exterior    view    of    San    Francisco's    new   high  pressure  salt  water 

pumping  plant,  showing  chimney  design  for  fuel  oil  practice. 
Here  is  a  view  of  the  housing  for  the  Townsend  Street  high  pressure  salt  water  pumping 
station  at  San  Francisco.  The  chimney  stack  as  shown  illustrates  the  best  and  most  per- 
manent type  of  design  for  fuel  oil  practice.  No  artificial  means  of  producing  a  draft  is 
employed  in  this  installation.  It  is  a  plant  kept  in  eternal  readiness,  should  disaster  ever 
again  visit  San  Francisco  as  happened  during  April,  1906,  in  the  days  of  the  great  fire. 

burning  out  of  the  brickwork.  For  satisfactory  operation  of 
stationary  boilers  it  is  necessary  to  keep  the  pressure  of  the 
gases  within  the  boiler  setting  slightly  lower  than  atmospheric 
pressure.  When  forced  draft  is  used  the  positive  pressure 
should  not  extend  beyond  the  ash  pit.  Forced  draft  is  used 
extensively  with  Mechanical  Atomizing  oil  burners,  where  owing 
to  the  small  area  for  air  admission  it  is  impossible  to  get  into 


270 


FUEL  OIL  AND  STEAM  ENGINEERING 


the  furnace  enough  air  for  high  overloads  by  means  of  natural 
draft. 

Induced  draft  can  be  used  instead  of  natural  draft  wherever 
desired.  It  is  cheaper  to  install  than  a  high  stack,  but  the  power 
required  to  drive  the  fan  makes  it  more  expensive  to  operate. 
It  is  of  especial  advantage  where  the  gases  escaping  from  the 
boiler  are  passed  through  an  economizer  to  absorb  some  of  their 
heat,  before  they  are  allowed  to  reach  the  chimney.  The 
economizer  introduces  added  frictional  resistance  to  the  gases 
so  that  extra  draft  is  required.  Besides  this,  the  economizer 
reduces  the  temperature  of  the  gases  to  such  an  extent  that  to 
obtain  sufficient  draft  without  a  fan  would  require  a  stack  of 
excessive  height.  By  installing  an  induced  draft  fan  between 


FIG.  168.- 


-Exterior  view  of  San  Bernardino  Plant  of  Southern  Sierras  Power 
Company  where  artificial  draft  is  employed. 


the  economizer  and  the  stack,  ample  draft  can  be  obtained 
regardless  of  the  height  of  the  stack  or  the  temperature  of  the 
gases. 

Induced  draft  is  also  of  value,  even  when  economizers  are  not 
employed,  in  cases  where  it  is  impracticable  or  undesirable  to 
build  a  stack  of  normal  height.  An  example  of  this  is  found  in 
the  power  plant  of  the  University  of  California,  where  a  high 
unsightly  stack  would  seriously  interfere  with  the  architectural 
features  of  the  university  buildings.  By  building  a  stack  only 
50  ft.  high,  and  supplementing  it  with  an  induced  draft  fan, 
this  difficulty  was  overcome. 


CHAPTER  XXXI 
CHIMNEY  GAS  ANALYSIS 

We  have  found  in  preceding  discussions  that  for  practical 
purposes  the  gases  passing  out  through  a  chimney  from  the 
central  station  boiler  are  usually  considered  to  be  composed  of 
carbon  dioxide,  oxygen,  carbon  mon- 
oxide and  nitrogen.  Since  these 
constituents  are  usually  determined 
volumetrically  we  shall  represent  them 
by  the  symbols  Vi}  F2,  V3,  and  F4, 
respectively.  We  shall  now  proceed 
to  a  discussion  of  the  usual  methods 
employed  in  determining  the  flue  gas 
analysis  during  the  boiler  test. 

The  Taking  of  the  Flue  Gas  Samples 
and  Analysis. — Certain  solutions  have 
been  found  in  the  chemist's  laboratory 
that  will  absorb  carbon  dioxide  and 
will  not  absorb  oxygen,  carbon  mo- 
noxide or  nitrogen.  Again  another 
solution  has  been  found  that  will 
absorb  oxygen  but  will  not  absorb 
carbon  monoxide  or  nitrogen.  And 
still  a  third  solution  has  been  found 
that  will  absorb  carbon  monoxide  but 
will  not  absorb  nitrogen.  If  then  a 
contrivance  can  be  set  up  so  that  a 
flue  gas  sample  may  be  successively 
washed  in  these  solutions,  a  means  is 
provided  for  determining  an  analysis 
by  volume. 

Orsat  Apparatus. — Let  us  then  see 
how  the  flue  gas  analysis  is  taken. 
The  apparatus  commonly  called  the 
Orsat  Apparatus  (see  Fig.  171)  con- 
sists of  a  wooden  case  with  removable  sliding  doors  which  con- 
tain a  measuring  tube  or  burette  B,  three  absorbing  bottles  or 

271 


FIG.  169. — A  carbon  dioxide 
recorder. 


272 


FUEL  OIL  AND  STEAM  ENGINEERING 


pipettes,  P'y  P",  and  P'".     In  addition  a  leveling  bottle  A  and 
connecting  tube  T  are  also  provided. 

The  tube  E  is  connected  to  the  point  in  the  flue  at  which 
the   sample   is  to .  be   taken.     The  instrument   is  first   set    in 


TO  BOILER  ROOM  INDICATOR 
TO  RECORDING  GAUGE 


ABSORPTION  CHAMBER 


INDICATING  ft        II  F>^^-«  FILTER 

COLUMN"—* 


WATER. 
JAR 

FIG.  170. — A  recorder  for  combustion  operation. 

From  the  discussion  in  the  text  it  may  be  inferred  that  a  knowledge  of  the  carbon  dioxide 
component  of  the  flue  gas  enables  us  to  judge  concerning  the  combustion  taking  place  in 
the  furnace.  The  principle  involved  in  the  type  of  carbon  dioxide  recorder  as  shown  is  that 
a  change  of  volume  in  a  gas  produces  a  change  of  pressure.  A  continuous  sample  of  the 
flue  gas  enters  at  A  and  in  passing  through  the  absorption  chamber  the  carbon  dioxide  is 
absorbed  and  consequently  a  reduction  in  pressure  takes  place.  By  the  calibration  of  suit- 
able manometer  tubes  the  instrument  may  be  made  to  read  the  carbon  dioxide  component 
direct. 

operation  by  closing  the  stop-cocks  /,  g,  and  e,  d  being  open. 
By  lowering  the  leveling  bottle  A,  a  sample  of  the  gas  is 
drawn  into  the  burette  B.  This  preliminary  sample  is  then 


CHIMNEY  GAS  ANALYSIS  273 

expelled  to  the  atmosphere  by  raising  the  bottle  A  and  allowing 
the  gas  thus  put  under  pressure  to  pass  out  through  a  by-pass  at 
d.  This  process  is  continued  until  it  is  considered  that  an  average 
sample  has  been  drawn  into  the  burette  B.  The  leveling  bottle 
A  is  next  lowered  so  as  to  cause  the  water  in  burette  B  to  come 
to  its  zero  mark.  By  raising  the  bottle  A  the  water  is  again 
forced  into  burette  B  and  the  gas  sample  expelled  through  stop- 
cock e  into  the  pipette  P'}  in  which  there  is  a  chemical  solution 


FIG.   171. — The  Orsat  apparatus. 

The  Orsat  apparatus  is  a  portable  instrument  contained  in  a  wooden  case  with  removable 
sliding  door  front  and  back,  as  shown  in  its  simplest  form  in  this  illustration,  taken  from 
the  report  of  the  Power  Test  Committee  of  the  American  Society  of  Mechanical  Engineers. 
It  consists  essentially  of  a  measuring  tube  or  burette,  three  absorbing  bottles  or  pipettes,  and 
a  leveling  bottle,  together  with  the  connecting  tubes  and  apparatus.  The  bottle  and  meas- 
uring tube  contain  pure  water;  the  first  pipette,  sodium  or  potassium  hydrate  dissolved  in 
three  times  its  weight  of  water;  the  second,  pyrogallic  acid  dissolved  in  a  like  sodium  hy- 
drace  solution  in  the  proportion  of  5  grams  of  the  acid  to  100  cc.  of  the  hydrate;  and  the  third, 
cuprous  chloride.  These  chemicals  are  sold  by  most  of  the  large  dealers.  Details  of  how 
this  apparatus  is  used  to  determine  the  chimney  gas  analysis  were  set  forth  in  a  previous 
discussion. 

that  absorbs  carbon  dioxide,  but  will  not  absorb  oxygen,  carbon 
monoxide  or  nitrogen. 

To  Ascertain  the  Carbon  Dioxide  Content  of  a  Flue  Gas. — 
Exactly  100  cc.  of  gas  were  originally  drawn  into  the  burette 
B.  If  now  the  leveling  bottle  A  is  again  lowered  to  draw  the 
gas  back  through  stop-cock  e,  the  volume  in  the  burette  will  be 
found  to  have  lessened  in  quantity  so  that  instead  of  reading 
zero  it  now  reads  NI  which  indicates  directly  the  volume  of  car- 
is 


274  FUEL  OIL  AND  STEAM  ENGINEERING 

bon  dioxide  that  was  present  in  the  gas,  for  evidently  this  volume 
has  been  absorbed  in  the  pipette  Pf .  Hence,  we  have 

Ti  =  Nl  (1) 

To  Ascertain  the  Oxygen  Content  of  a  Flue  Gas. — In  a  similar 
manner  the  gas  sample  in  the  burette  B  is  now  forced  through 
pipette  P"j  in  which  is  a  solution  that  will  absorb  free  oxygen  in 
the  sample  but  will  not  absorb  carbon  monoxide  or  nitrogen.  By 
means  of  the  leveling  bottle  A,  the  sample  is  next  drawn  back 
into  the  burette  B  and  a  reading  JV2  noted.  It  is  now  evident 
that  the  oxygen  content  of  the  flue  gas  may  be  computed  from 
the  formula 

V2  =  N,  -  V,  (2) 

To  Ascertain  the  Carbon  Monoxide  Content  of  a  Flue  Gas. 

The  pipette  P'"  similarly  contains  a  solution  which  readily  ab- 
sorbs the  carbon  monoxide  present  in  the  gas,  but  will  not  absorb 
nitrogen.  Hence  we  proceed  as  in  the  two  former  instances 
and  return  the  gas  sample  to  the  burette  which  now  reads  N3. 
Consequently  the  carbon  monoxide  which  was  present  in  the 
flue  gas  is  obtained  from  the  formula 

V,  =  N,  -  (V,  +  F2)  (3) 

To  ascertain  the  Nitrogen  Content  of  a  Flue  Gas. — We  assume 
that  all  of  the  gas  which  remains  in  the  sample  is  nitrogen.  Con- 
sequently the  nitrogen  content  is  obtained  from  the  formula 

74  =  100  -  (V,  +  V2  +  78)  (4) 

An  Approximate  Check  on  the  Orsat  Analysis. — Air  is  found 
by  weight  to  have  76.85  per  cent,  nitrogen  and  23.15  per  cent, 
oxygen.  By  volume  this  analysis  will  be  found  to  be  79.09  per  cent, 
nitrogen  and  20.91  per  cent,  oxygen.  Since  1  unit  by  volume  of 
oxygen  forms  1  unit  by  volume  of  carbon -dioxide  in  the  burning 
of  pure  carbon  the  actual  percentage  of  nitrogen  in  the  chimney 
gases  is  not  altered  but  should  remain  79.09  per  cent,  if  perfect 
combustion  is  maintained. 

On  the  other  hand,  when  imperfect  combustion  is  under  way, 
or  in  other  words,  when  some  carbon  monoxide  is  being  formed 
1  unit  by  volume  of  oxygen  forms  2  units  by  volume  of  carbon 
monoxide.  Hence  when  pure  carbon  is  the  fuel,  the  sum  of  the 
percentages  of  carbon  dioxide,  oxygen,  and  J-£  the  carbon  monox- 
ide must  be  in  the  same  ratio  to  the  nitrogen  present  as  the  oxygen 


CHIMNEY  GAS  ANALYSIS 


275 


in  the  air  is  to  the  nitrogen  component,  namely  as  20.91  :  79.09. 
This  is  a  convenient  check  upon  a  flue  gas  analysis  in  the  prog- 
ress of  the  experiment.  Thus  if  an  analysis  of  chimney  gas  is 
found  to  contain  by  volume  9.5  per  cent,  carbon  dioxide,  10.2 
per  cent,  carbon  monoxide,  5.2  per  cent,  oxygen,  and  75.1  per 
cent,  nitrogen,  according  to  this  proportion,  we  should  have 

10 


9.5  +  5.2 


:  75.1  =  20.91  :  79.09 


Upon  investigation  this  will  be 
found  to  be  approximately  true 
and  well  within  the  limit  of  ex- 
perimental accuracy. 

As  California  crude  oil  contains 
usually  about  11  per  cent,  of 
hydrogen,  the  ready  checking 
above  indicated  proves  of  no 
avail  since  the  hydrogen  content 
is  not  taken  account  of  in  the 
Orsat  or  flue  gas  analysis.  As 
the  relationship  serves,  however, 
to  clinch  our  ideas  of  volumetric 
proportions  of  entering  air  and 
outgoing  flue  gases,  it  is  well  to 
bear  it  in  mind. 

In  boilers  fired  by  coal  contain- 

ing little  hydrogen  the  CO  does 


FIG.  172.—  Hays  gas  analyzer,  con- 


not     Usually    exceed    1    Or    2   per      venient  for   carrying   from   place   to 

cent,  and  the  sum  of  the  Orsat 

readings  CO2+  O  +  CO  is  usually  beween  20  and  21  per  cent. 
When  burning  oil,  on  the  other  hand,  the  sum  of  these  readings 
may  be  as  low  as  16  or  17  per  cent,  due  to  the  large  proportion 
of  hydrogen  in  the  fuel,  which  means  an  apparent  nitrogen  con- 
tent of  83  or  84  per  cent.  The  reason  for  this  is  that  the  water 
vapor  formed  by  the  burning  of  hydrogen  condenses  in  the  Orsat 
apparatus  and  occupies  practically  no  volume,  but  the  oxygen 
which  unites  with  the  hydrogen  brings  with  it  the  same  propor- 
tion of  nitrogen  as  does  the  oxygen  that  unites  with  the  carbon. 
Consequently  the  Orsat  indicates  a  larger  proportion  of  nitrogen 
than  would  occur  if  the  fuel  were  pure  carbon. 

Chemical  Formulas  for  Preparing  the  Absorption  Solutions. 
The  bottle  A  and  the  measuring  tube  or  burette  B  contain  pure 


276  FUEL  OIL  AND  STEAM  ENGINEERING 

water  only,  while  the  first  pipette  P'  in  which  carbon  dioxide  is 
absorbed  contains  sodium  hydrate  dissolved  in  three  times  its 
weight  of  water.  The  second  pipette  P"  in  which  oxygen  is 
absorbed  contains  Pyrogallic  acid  dissolved  in  sodium  hydrate 
in  the  proportion  of  five  grams  of  the  acid  to  100  cc.  of  the 
hydrate,  and  in  the  third  pipette  wherein  carbon  monoxide  is 
absorbed  cuprous  chloride  is  contained.  These  chemicals  are 
sold  by  most  of  the  large  dealers.' 

Another  series  of  formulas  which  work  equally  well  and  in 
many  cases  are  more  easily  prepared,  are  the  following: 

To  absorb  the  carbon  dioxide,  potassium  hydroxide  is  used, 
and  is  made  by  diluting  500  grams  of  commercial  potassium 
hydroxide  in  one  quart  of  water.  To  absorb  the  oxygen,  potas- 
sium-Pyrogallite  is  used  wherein  five  grams  of  solid  acid  in  100 
cc.  of  potassium  hydroxide  above  mentioned  is  prepared.  When 
over  28  per  cent,  of  oxygen  is  present,  it  is  necessary  to  use  12 
grams  of  commercial  potassium  hydroxide  to  100  cc.  of  water. 
To  absorb  the  carbon  monoxide,  cuprous  chloride  is  used  which 
is  prepared  by  covering  the  bottom  of  a  quart  measure  with 
cuprous  chloride  (CuO)  to  a  depth  of  %ths  of  an  inch.  The 
measure  is  then  filled  with  hydrochloric  acid,  shaken  and  allowed 
to  stand  until  it  becomes  colorless.  The  copper  wire  is  then 
placed  in  the  solution  and  left  to  stand  for  a  number  of  hours. 

The  Hemphel  Apparatus  for  Determining  the  Hydrogen 
Content. — It  is  seen  from  the  above  description  that  no  means  are 
provided  to  ascertain  whether  or  not  the  hydrogen  content  of  the 
fuel  is  being  properly  consumed.  This  determination  can  only 
be  made  by  the  refined  laboratory  apparatus  of  the  chemist. 
The  authors  consider  that  such  a  test  is  beyond  the  scope  of  this 
work,  hence  the  description  of  the  Hemphel  apparatus  and  its 
operation  will  not  be  undertaken  in  these  pages.  Standard 
works  on  this  subject  are,  however,  available  in  all  chemical 
engineering  libraries  for  those  who  desire  to  go  into  this  subject. 
Except  for  refined  tests  covering  certain  particular  problems  in 
combustion  the  Orsat  analysis  of  flue  gases  is  considered  suffi- 
ciently accurate  for  power  plant  practice.  Indeed,'  in  most 
instances,  as  we  shall  see,  the  determination  of  the  carbon  dioxide 
component  alone  gives  us  sufficient  information  for  ordinary 
operating  conditions. 

Gas  Analysis  in  the  Power  Plant. — The  simple  Orsat  apparatus 
is  used  very  extensively  in  many  power  plants.  It  is  reliable  and 


CHIMNEY  GAS  ANALYSIS 


277 


accurate  and  its  only  objections  are  that  it  is  a  somewhat  delicate 
instrument  and  requires  careful  manipulation. 

There  are  on  the  market  other  instruments  that  are  more 
rugged  in  construction  and  therefore  more  suitable  for  power 
plant  work,  by  which  it  is  possible  to  determine  the  CO2  only. 
While  for  any  scientific  investigation  or  accurate  test  it  is  neces- 
sary to  determine  the  oxygen  and  CO  as  well  as  the  CO2,  there  are 
many  cases  in  practical  operation  where  a  determination  of  the 
CO2  alone  is  very  valuable.  There- 
fore, the  simple  instrument  by 
which  this  can  be  done  has  a  useful 
place  in  power  plant  work. 

One  of  these  instruments  which 
is  illustrated  in  Fig.  173  is  known 
as  the  Dwight  CO2  Indicator.  This 
instrument  consists  of  a  metallic 
vessel,  into  which  is  pumped  a 
charge  of  the  flue  gas  to  be  analyzed. 
The  vessel  contains  a  small  quantity 
of  Caustic  Potash  solution  for  the 
purpose  of  absorbing  the  CO2  in  the 
sample.  As  soon  as  the  gas  is 
taken  into  the  receiver  the  cocks  are 
closed,  and  the  instrument  is  shaken 
to  thoroughly  mix  the  gas  with  the 
absorbent  solution,  thus  removing 
the  CO2  content.  A  small  amount 


FIG.  173.  — CO2  indicator. 
Dwight  Mfg.  Co.,  Chicago,  Pat. 
applied  for. 


of  mineral  oil  floats  on  top  of  the  Caustic  Solution  to  keep%the 
gas  from  coming  in  contact  with  the  caustic  until  after  the  cocks 
are  closed  and  the  instrument  shaken.  Removing  the  CO2  in 
the  gas  reduces  either  its  volume  or  its  pressure.  In  this  case,  the 
volume  remains  constant,  and  consequently  the  removal  of  the 
CO2  reduces  the  pressure,  in  accordance  with  Boyle's  Law  (page 
44)  .  The  reduction  in  pressure  is  measured  by  a  small  vacuum 
gauge,  which  is  calibrated  to  read  direct  in  percentage  of  CO2. 

Another  instrument  known  as  the  Pocket  CO2  Indicator 
is  illustrated  in  Fig.  174.  This  is  a  compact  portable  ins- 
trument that  operates  on  the  same  principle  as  the  Orsat,  and 
makes  accurate  C02  determinations. 

Conclusion  on  the  Orsat  Analysis.  —  By  care  and  a  little  pa- 
tience, the  experimenter  will  find  that  the  Orsat  analysis  as 


278 


FUEL  OIL  AND  STEAM  ENGINEERING 


above  set  forth  can  be  taken  easily  and  quite  accurately,  and 
thus  a  splendid  lot  of  data  obtained  wherewith  steam  boiler 
economy  and  operation  can  be  checked.  If  wrong  conditions 
of  combustion  are  found  to  prevail  the  proper  adjustments  can 
then  be  made  in  the  furnace  and  its  accessories. 

We  shall  next  proceed  to  formulate  some  equations  whereby 
the  data  gained  from  the  flue  gas  analysis  may  be  thrown  into 
more  useful  analytical  form. 


FIG.  174. — Pocket    CO2    indicator    (patented)   made  by  Bacharach  Industrial 
Instrument  Co.,  Pittsburg,  Pa. 


CHAPTER  XXXII 

ANALYSIS    BY    WEIGHT,    AND    AIR     THEORETICALLY 
REQUIRED  IN  FUEL  OIL  FURNACE 

In  the  last  discussion  it  was  found  that  Orsat  analyses  of 
chimney  gases  are  always  made  volumetrically.  In  computing 
combustion  data  from  these  analyses,  however,  it  is  often  nec- 
essary to  have  the  proportions  or  percentages  by  weight  instead 


FIG.  175.- — Carbon  dioxide  recording  machine  located  in  the  Long  Beach  Plant 
of  the  Southern  California  Edison  Company, 

of  by  volume.  The  volumes  of  carbon  dioxide,  oxygen,  carbon 
monoxide,  and  nitrogen  which  constitute  the  chimney  gas  analy- 
sis of  a  sample  volume  by  means  of  the  Orsat  apparatus  will  be 
represented  by  V\,  72,  V^  V4,  respectively  in  this  discussion. 

279 


280 


FUEL  OIL  AND  STEAM  ENGINEERING 


Let  us  now  see  how  we  may  transfer  this  relationship  so  that 
proportions  by  weight  of  M\,  M2,  Ms  and  M4  pounds  may 
respectively  set  forth  the  constituents  of  a  flue  gas  sample  of 
weight  M  pounds.  Since  we  are  only  in  search  of  proportions 
by  weight — that  is  a  ratio  of  MI  to  M,  Mz  to  M  etc.,  it  is  evi- 
dently not  necessary  to  actually  know  the  quantitative  values 
of  the  weights  involved. 


FIG.  176. — Recording  thermometer  and  draft  gage  on  Stirling  boilers.     Pacific 
Gas  and  Electric  Company,  station  C,  Oakland,  Cal. 

Fundamental  Laws  Involved. — In  a  previous  discussion  we 
found  (see  page  48)  that  all  perfect  gases  follow  the  composite 
law — namely,  that  at  any  particular  state  the  product  of  its 
pressure  p  and  volume  V  is  equal  to  the  product  of  its  weight 
M  and  absolute  temperature  T  multiplied  by  a  constant  R, 
or  mathematically  expressed 

pV  =  MET 
Hence,  we  may  at  once  write  the  respective  mathematical  rela- 


ANALYSIS  BY  WEIGHT  281 

tionships  for  the  carbon  dioxide,  oxygen,  carbon  monoxide,  and 
nitrogen  of  the  flue  gas. 

It  is  to  be  remembered  that  in  the  case  under  consideration 
the  pressure  p  and  the  temperature  T  have  the  same  value  for 
each  component  in  the  flue  gas;  consequently,  we  shall  not  put 
any  individual  subscript  for  the  pressure  p  and  temperature  T, 
so  that  we  may  write  these  individual  expressions  as  follows: 

pV1  =  M&iT  or  Ml  = 


P2  =      Z2     or      2  = 

riii 

PV3  =  M3R3T  or  M,  =  -|^ 

R31 

pV>  =  MJt<T  or  M4  = 
and  for  the  gas  as  a  whole,  we  have 

PV   -  MRT  or  M  -- 


In  our  previous  discussion  on  the  elementary  laws  of  gases,  it 
was  also  found  mathematically  that  the  constant  R  for  any 
perfect  gas  is  obtained  by  dividing  1544  by  the  molecular  weight 
of  the  gas  in  question  (see  page  47). 

From  any  book  on  elementary  chemistry  we  find  the  molecular 
weight  m  of  carbon  dioxide  (CO2)  is  44,  that  of  oxygen  (O2)  is 
32,  that  of  carbon  monoxide  (CO)  is  28,  and  that  of  nitrogen 
(N2)  is  28. 

Relationship  of  a  Component  Weight  to  the  Whole.  —  Bearing 
this  in  mind,  it  is  seen  from  the  above  mathematical  relationships 

1544 
that,  since  R  =  -"     —  >  we  have 


m 


M    =  =        ^        =  fCrn  V    if  K  = 


154477  1544T 


"  R2T     '  1544 T 

pV3  _  m3pV3  _    ,r     T. 
3==  &T==  1644JP  ~     m'V° 


"<  --  S =  iw  -  '-^ 

*-ft"^-*^ 


282  FUEL  OIL  AND  STEAM  ENGINEERING 

But  Mi  +  M2  +  MB  +  M*  =  M 

M  = 


Hence 


Let  C8  -- 
. ' .  M  =  KC8 
Also  MI  =  KmiVi 

Mi      KmiVi 
M          KC8 


C8 


(1) 


FIG.  177. — View  of  the  float  arrangements,  showing  the  valves  which  control 
the  inlet  and  outlet  of  oil  from  storage  tanks  of  Long  Beach  Plant,  Southern 
California  Edison  Company. 

A  Concrete  Rule  for  Conversions. — This  last  equation  now 
gives  us  a  simple  and  ready  rule  for  determining  proportions  by 
weight  if  the  proportions  by  volume  are  given.  In  other  words, 
this  rule  may  be  stated  as  follows : 

In  any  analysis  by  volume,  the  analysis  by  weight  is  found  by 
first  summing  the  products  formed  by  multiplying  each  com- 
ponent volume  by  its  particular  molecular  weight.  If  now  this 
summation  Cs  is  divided  into  the  product  of  a  component  volume 


ANALYSIS  BY  WEIGHT 


283 


and  its  particular  molecular  weight,  the  proportion  by  weight  of 
that  component  is  at  once  ascertained. 

An  Illustrative  Example. — Thus,  a  flue  gas  analysis  shows  the 
following  proportions  by  volume:  carbon  dioxide  (CO2)  0.086; 
oxygen  (O2)  0.110;  carbon  monoxide  0.011;  and  nitrogen  (N2) 
0.793  per  cent.  Let  us  determine  the  proportions  by  weight 
present  in  this  particular  flue  gas. 

Since  the  molecular  weights  of  carbon  dioxide,  oxygen,  carbon 
monoxide  and  nitrogen  are  respectively  44,  32,  28,  and  28,  we 
find  that  miVi  is  3.782,  ra2F2  is  3.520,  m3y3  is  0.308,  and  m474  is 
22.200.  The  sum  of  these  products  Cs  is  found  to  be  29.810. 
Hence  since  m\V\  is  3.782,  we  now  find  that  the  carbon  dioxide 
component  obtained  by  dividing  3.782  by  29.810  is  0.1270.  Simi- 
larly for  the  oxygen  component  the  proportion  by  weight  is 
0. 1 182 ;  for  the  carbon  monoxide  component  it  is  0.0103 ;  and  for  the 
nitrogen  component  we  have  0.7453.  As  a  check  on  our  work  we 
find  that  the  sum  of  these  separate  components  is  unity  as  it 
should  be.  Or  expressed  in  percentages,  we  would  have  for  a 
volumetric  analysis  consisting  of  8.6  per  cent,  carbon  dioxide, 
11.0  per  cent,  oxygen,  1.1  per  cent,  carbon  monoxide,  and  79.3  per 
cent,  nitrogen,  that  the  percentages  by  weight  become  12.70  per 
cent,  carbon  dioxide,  11.82  per  cent,  oxygen,  1.03  per  cent,  carbon 
monoxide,  and  74.53  per  cent,  nitrogen,  which  foot  up  100  per 
cent,  in  either  case  and  thus  check  our  work. 

A  Suggested  Form  of  Tabulation. — To  expedite  computation 
the  work  set  forth  in  the  above  discussion  may  be  tabulated. 
Below  we  have  a  form  of  tabulation  which  will  prove  useful  for 
such  transformations: 


Constituents 

Volume 

Mol.  Wt. 

mV 

mV 
Cs 

CO2  
O2 

0.086 
0  110 

44 
32 

3.782 
3  ,520 

0.1270 
0  1182 

CO  

0  Oil 

28 

0  308 

0  0103 

N2  

0.793 

28 

22.200 

0.7453 

1.000 

Cs  =  29.810 

1  .  0000 

Weight  of  Air  Theoretically  Required  for  Perfect  Fuel  Oil 
Combustion. — For  economic  combustion  in  the  furnace  a  certain 
percentage  of  air  over  and  above  that  theoretically  required  for 


284  FUEL  OIL  AND  STEAM  ENGINEERING 

perfect  combustion  is  necessary.  This  is  due  to  the  fact  that  it 
is  practically  impossible  to  bring  all  of  the  entering  air  into  inti- 
mate contact  with  the  heated  carbon,  hydrogen,  and  other  com- 
bustible ingredients  of  the  fuel;  consequently,  unless  an  excess 
of  air  is  admitted  some  of  these  ingredients  will  pass  out  of  the 
chimney  unconsumed.  Good  practice  dictates  from  15  to  20 
per  cent,  excess  of  air  as  the  proper  ratio  for  economic  fuel  oil 
consumption  in  the  furnace. 

In  order  then  to  know  when  this  ratio  is  properly  established 
we  must  have  some  means  of  ascertaining  the  air  theoretically 
required  for  perfect  combustion  as  well  as  that  actually  used  in 
the  furnace  per  pound  of  fuel. 

Correction  for  Oxygen  Appearing  in  Fuel  Analysis. — In  the 
composition  of  fuels  varying  quantities  of  oxygen  (O)  are  found 
by  analysis  to  be  present.  While  in  a  sense  this  is  in  a  free  state, 
still  the  hydrogen  content  is  reduced  in  heating  value  by  an 
amount  equal  to  the  combining  weight  of  this  oxygen  (0)  with  the 
hydrogen  (H).  Experimentally  we  find  that  8  Ib.  of  oxygen 
combine  with  1  Ib.  of  hydrogen.  Hence,  so  far  as  heating 
value  is  concerned  and  indeed  so  far  as  outside  oxygen  may  be 
required  for  combustion  of  the  hydrogen,  the  actual  hydrogen 

content  is  reduced  in  value  to  [H  -  •    ~  j  >  where  H  represents  the 

proportion  by  weight  of  hydrogen  and  0  the  proportion  by 
weight  of  oxygen  present  in  the  fuel. 

Oxygen  Theoretically  Required  for  Fuel  Combustion. — The 
oxygen  theoretically  required  is  computed  from  a  consideration 
of  the  fundamental  chemical  reactions  that  take  place  in  the 
furnace. 

Thus,  from  chemistry  we  learn  that  to  completely  burn  1 
Ib.  of  pure  carbon  3%2ths  of  a  pound  of  oxygen  are  required. 
Again  to  burn  1  Ib.  of  pure  hydrogen  8  Ib.  of  oxygen  are  required. 
And  in  the  third  place  to  burn  1  Ib.  of  pure  sulphur  1  Ib.  of  oxygen 
is  required. 

If  now  1  Ib.  of  fuel  oil  is  found  by  analysis  to  contain  C  parts 
by  weight  of  carbon,  H  parts  by  weight  of  hydrogen,  0  parts 
by  weight  of  oxygen,  and  S  parts  by  weight  of  sulphur,  it  is 
evident  that  the  weight  of  oxygen  required  per  pound  of  fuel 
oil  for  perfect  combustion  is  from  the  above  discussion 

32  c  4-  *  (rr 
12  C  +  8  (H  ~ 


ANALYSIS  BY  WEIGHT  285 

Air  Required  per  Pound  of  Fuel  Burned.  —  Since  air  is  com- 
posed of  0.2315  parts  by  weight  of  oxygen,  the  theoretical  weight 
of  air  Mta  necessary  to  supply  the  oxygen  above  required  for 
perfect  combustion  is 

S 


0.2315  82315  O2315 

11.52C  +  34.56  fl"  --       +  4.32S  (2) 


An  Illustrative  Example.  —  Fuel  analyses  are  always  given  in 
proportions  or  percentages  by  weight.  In  a  certain  boiler  test 
a  sample  pound  of  the  fuel  oil  analyzed  as  follows:  carbon  81.52 
per  cent.  ;  hydrogen  11.01  per  cent.  ;  sulphur  0.55  per  cent.  ;  and  oxy- 
gen 6.92  per  cent.  Let  us  then  compute  the  weight  of  air  Mta 
theoretically  required  to  burn  a  pound  of  this  oil. 

In  applying  the  formula  above  deduced,  it  must  be  remembered 
that  the  symbols  there  given  for  hydrogen,  oxygen,  and  sulphur 
contents  are  in  proportions  and  not  percentages.  Bearing  this 
in  mind  we  have  by  substitution  — 


Mta=  11.52  X  0.8152  +  34.56  (0.1101-  )  +4.32X0.0055  = 

12.92  Ib. 

Having  now  learned  how  to  convert  the  Orsat  analysis  by 
volume  into  proportions  by  weight  and  also  to  ascertain  the 
air  theoretically  required  per  pound  of  fuel,  we  shall  in  the  next 
discussion  determine  actual  combustion  data  by  means  of  these 
stepping  stones  in  computation. 


CHAPTER  XXXIII 


COMPUTATION    OF    COMBUSTION    DATA   FROM    THE 
ORSAT  ANALYSIS 

N  the  last  chapter  the  reader  was 
shown  in  detail  how  to  convert  the 
Orsat  analysis  by  volume  to  an 
analysis  by  weight.  We  now  as- 
sume that  the  volumetric  content 
of  a  sample  of  flue  gas  has  been 
taken  and  that  Vi,  VZ}  F3,  and  F4 
represent  quantitatively  the  carbon 
dioxide,  oxygen,  carbon  monoxide, 
and  nitrogen  contents  respectively. 

If  accurately  ascertained  these 
components  of  the  flue  gas  enable 
the  engineer,  as  has  been  previously 
hinted,  to  compute  important  eco- 
nomic conclusions  on  the  com- 
bustion phenomena  that  are  taking 
place  in  the  boiler  furnace.  It  is 
important  to  know,  for  instance, 
not  only  the  air  that  is  theoretically 
required  for  perfect  combustion,  but 
the  actual  weight  of  air  that  is  being 
admitted  to  the  furnace  per  pound  of  fuel  consumed.  The 
weight  of  the  flue  gases  per  pound  of  fuel  burned  is,  too,  of 
importance,  as  well  as  many  other  details  that  may  now  be 
ascertained.  Several  different  methods  of  utilizing  the  flue  gas 
analysis  have  been  proposed  to  arrive  at  combustion  data. 
Let  us  now  proceed  to  their  consideration  and  discussion. 

Air  Actually  Supplied  to  Furnace  per  Pound  of  Fuel  Burned. 
There  are  three  formulas  that  enable  us  to  compute  the  actual 
quantity  of  air  entering  the  furnace  if  we  know  the  analysis  of 
the  chimney  gases. 

286 


FIG.  178.  —  Boiler  front— oil 
fired;  showing  gage  for  measur- 
ing chimney  draft. 


COMBUSTION  DATA  FROM  THE  ORSAT  ANALYSIS     287 

From  volumetric  experiments  in  chemistry  we  learn  that  Vi 
units  by  volume  of  oxygen  form  Vi  units  by  volume  of  carbon 
dioxide,  thereby  burning  V\  units  by  volume  of  carbon  in  the 
fuel.  The  unit  volume  of  carbon  is,  of  course,  to  be  considered 
as  a  gas  and  riot  in  its  solid  state  as  ordinarily  encountered. 
Since  carbon  does  not  exist  in  a  gaseous  state  at  ordinary  pressures 
and  temperature,  the  reasoning  involved  is,  of  course,  incorrect 
in  that  particular.  However,  for  purposes  of  deriving  the 
formula  there  is  no  inaccuracy  introduced  by  the  assumption 
that  carbon  in  a  gaseous  state  acts  according  to  all  well  known 
laws  of  chemistry. 

On  the  other  hand,  volumetric  experiments  in  chemistiy  tell 

T7- 

us  that  -7^  units  by  volume  of  oxygen  form  F3  units  by  volume 

of  carbon  monoxide,  thereby  burning  V3  units  by  volume  of 
carbon  in  the  fuel. 

Again,  F2  units  of  oxygen  appearing  in  the  flue  gas  have 
evidently  necessitated  the  entrance  of  F2  units  of  oxygen  from 
the  air  without,  but  have  required  no  carbon  from  the  fuel. 

V3 

Summing  up,  we  find  that  (V}  +  -^   +  F2)  units  by  volume 

of  oxygen  have  required  (V\  +  F3)  units  by  volume  of  carbon 
in  the  fuel  for  the  formation  of  the  particular  analysis  shown 
in  the  flue  gas. 

Therefore,  one  unit  by  volume  of  carbon  in  the  fuel  would 
require 


Fi  +  F3 

units  by  volume  of  entering  oxygen. 

A  unit  volume  of  carbon,  however,  weighs  12  pounds,  while 
a  similar  unit  volume  of  oxygen  weighs  32  pounds.  Hence,  for 
every  unit  weight  of  carbon  consumed  in  the  furnace 

32        Fl+T+72 
12  >       Vl  +  F3 

units  by  weight  of  oxygen  are  required.  Air  has  by  weight 
0.2315  proportions  of  oxygen.  Hence  if  C  units  by  weight  of 
carbon  are  found  in  each  pound  of  fuel,  the  actual  weight  of 


288  FUEL  OIL  AND  STEAM  ENGINEERING 

air  Mc  admitted  to  the  furnace  to  burn  carbon  per  pound  of  fuel 
burned  is 


V  !.+     *-  + 


TUT       _ 

" 


12       0.2315 


V,  +-f  72 
.'.Mc==  11.52  >        Vi+v^     XC  (1) 

It  is  to  be  remembered  that  the  derivation  of  this  formula  thus 
far  has  not  taken  into  account  the  hydrogen  content  of  the  fuel. 
Since  the  Orsat  analysis  condenses  the  water  vapor  formed  by 
the  burning  of  the  hydrogen  with  the  entering  oxygen  of  the  air 
as  the  sample  enters  the  first  tube  of  the  apparatus,  the  actual 
Orsat  analysis  indicates  volumetric  proportions  for  the  dry  flue 
gas  only.  We  can,  however,  if  we  know  the  hydrogen  content 
present  in  the  fuel,  make  a  correction  or  rather  addition  to  the 
above  formula  so  that  the  relationship  will  correctly  represent 
the  total  admission  of  air  into  the  furnace  under  test. 

In  the  previous  chapter  it  was  shown  that  if  a  fuel  analysis 
indicates  H  units  of  hydrogen  by  weight  and  0  units  of  free 
oxygen  by  weight  that  the  actual  hydrogen  available  for  combus- 

tion is   [H  —  -Q)  units  by  weight. 

\  o/ 

It  has  been  seen  too  that  1  Ib.  of  hydrogen  requires  for 
its  burning  8  Ib.  of  oxygen,  and  that  air  contains  0.2315 
proportions  by  weight  of  oxygen.  Hence  the  weight  of  air 
necessary  to  burn 

(H  -  g-j  pounds  of  hydrogen  is 


9315 


34.  56  (#  -^pounds. 


Therefore,  the  total  air  M  a  admitted  to  the  furnace  per  pound 
of  fuel  oil  burned  is 


1         -        2 

Ma  =  11.52  X  —v-^rT  —  X  C  +  34.56  (H  -  ^} 
v  i  ~     r  3  *  o/ 


V1  +-+  F2 

~r 

An  Illustrative  Example.  —  A  certain  California  oil  by  chemical 
analysis  is  found  to  contain  81.52  per  cent,  carbon;  11.01  per  cent. 
hydrogen;  0.55  per  cent,  sulphur;  and  6.92  per  cent,  oxygen. 


COMBUSTION  DATA  FROM  THE  ORSAT  ANALYSIS     289 

The  flue  gas  of  a  boiler  under  test  using  this  oil  was  found  by 
Orsat  analysis  to  contain  8.6  per  cent,  carbon  dioxide;  9.0  per 
cent,  oxygen;  1.1  per  cent,  carbon  monoxide;  and  81.3  per  cent, 
nitrogen.  Let  us  by  means  of  the  above  formula  compute  the 
air  actually  admitted  to  the  furnace  per  pound  of  oil  burned  in 
the  test.  Before  substitution  we  must  remember  that  the  above 
formula  is  expressed  in  proportions  and  not  in  percentages. 
Substituting  then,  with  this  in  mind,  we  have 

M      -  11  52  X°-086  +°  -0055  +°-°9  X  0  8152 
0.086  +  0.011 

+  34.56  X  (0.1101  -.-^j~\  =  21.1  Ib. 

A  Second  Formula  for  Ascertaining  Air  Actually  Admitted  to 
the  Furnace. — Let  us  next  deduce  a  formula  recommended  by  the 
American  Society  of  Mechanical  Engineers  for  the  determination 
of  the  air  supplied  to  the  furnace  per  pound  of  fuel  consumed. 

In  the  deduction  of  the  last  formula  it  was  seen  that  the  enter- 
ing oxygen  combines  with  (Vi  +  F3)  units  by  volume  of  carbon 
in  the  fuel.  With  this  entering  oxygen,  however,  is  associated 
Vi  units  by  volume  of  nitrogen.  Hence  for  each  unit  by  volume 

of  carbon  consumed  in  the  furnace  ly   _L  y  )  un^s  by  volume  of 

nitrogen  enter  with  the  oxygen  into  the  furnace.  Since  one 
unit  of  carbon  by  volume  weighs  1%gths  of  the  weight  of  one 
unit  by  volume  of  nitrogen,  we  have  that  for  every  pound  of 
carbon  burned  in  the  furnace 

28       _        74 
12  >       7i  +  7, 

pounds  of  nitrogen  enter  from  without.  But  air  is  0.7685  parts 
by  weight  nitrogen.  Hence  if  fiuel  oil  contains  C  parts  by  weight 
of  carbon,  for  every  pound  of  fuel  oil  burned  in  the  furnace,  the 
weight  of  air  Ma  drawn  in  from  without  is 

28  74  1 


+  78)       0.7685 
.-.Ma  =  3.032 


An  Illustrative  Example. — Taking  as  an  example  the  data  set 
forth  in  illustrating  the  first  formula  deduced  for  ascertaining 

19 


290  FUEL  OIL  AND  STEAM  ENGINEERING 

the  air  actually  admitted  to  the  furnace,  we  have  by  substituting 
in  this  second  formula  that 


=  3'032  (o. 


° 


0860.01l 

Weight  of  Dry  Flue  Gas  per  Pound  of  Fuel.  —  Since  the  entering 
air  above  computed  combines  with  one  pound  of  fuel,  we  may 
ascertain  the  weight  of  flue  gas  per  pound  of  fuel  oil  consumed  by 
simply  adding  unity  to  the  weight  of  air  actually  admitted  to  the 
furnace. 

Let  us,  however,  deduce  a  formula  directly  for  this  computation 
and  check  by  numerical  comparison  the  results  obtained  by  the 
former  methods. 

To  convert  an  analysis  by  volume  into  an  analysis  by  weight 
it  has  been  shown  that  if  these  components,  carbon  dioxide 
(CO2),  oxygen  (02),  carbon  monoxide  (CO),  and  nitrogen  (N2) 
are  respectively  FI,  F2,  V3  and  F4  by  volume,  then  by  weight 
according  to  the  formula  derived  in  the  last  discussion,  they  will 
prove  to  be 


wherein  Cs  is  obtained  by  summing  up  all  products  formed  by 
multiplying  each  component  volume  by  its  molecular  weight. 
For  every  pound  of  carbon  dioxide  (CO2)  formed  1%4  lb.  of 

carbon   are   consumed  in  the  fuel  oil.     Hence  to  form  ——  Mb. 


of  carbon  dioxide  it  is  evident  that  (      of  —^  lb.  of  carbon  are 


consumed  in  the  fuel  oil.     But  m\  for  carbon  dioxide  (CO2)   is 

1  2F 
44.     Hence  this  quantity  becomes     r  l- 

Gg 

Similarly,  since  each  pound  of  carbon  monoxide  (CO)  in  its 
formation  requires  J%8  lb.  of  carbon  from  the  fuel  oil,  for  the 


formation  of  — ^ —  lb.  of  carbon  monoxide  (CO),  we  must  burn 

6Qof     i  3)lb.  of  carbon.     But  w3  for  carbon  monoxide  (CO) 
O  V-/  &       I 

is  28. 

12F 
Hence  this  quantity  becomes    r     • 

Gs 


COMBUSTION  DATA  FROM  THE  ORSAT  ANALYSIS     291 

The  free  oxygen  and  the  free  nitrogen  in  the  flue  gas  have  of 
course  required  no  carbon  of  the  fuel.     Therefore,  for  M   Ib. 
of  chimney  gas  there  will  be  required 
12Fi       12r,       12 

~cT    ~5T    "£(FlH 

units  of  carbon;  or  reciprocally,  one  pound  of  carbon  will,  of 

C 

course,  form  10/T/    *    T7  .  units   bv    weight    of   flue  gas  and  C 
iZ( KIT-  v s) 

parts  of  carbon  by  weight  in  the  fuel  will  form  Mg  Ib.  of  flue  gas 
which  may  be  computed  from  the  formula 

M"  =    "  12(F,  +  F3) 

But  the  molecular  weight  for  carbon  dioxide  is  44,  for  oxygen 
it  is  32,  for  carbon  monoxide  it  is  28,  and  for  nitrogen  it  is  28, 
therefore  for  Cs  we  have 

C8  ==  447!  -f  3272  +  2873  +  28  74 
447i  +  3272  +  28V 3  +  2874 


or  M0  =  C 


Fa) 

^  ±^4  (4) 


An  Illustrative  Example. — Let  us  now  use  the  same  experi- 
mental data  as  in  the  previous  examples  and  compute  the  pounds 
of  dry  flue  gas  that  were  formed,  as  indicated  by  the  data  from 
the  Orsat  analysis. 

It  is  to  be  noted  in  passing  that  all  of  these  computations  based 
simply  upon  the  Orsat  analysis  give  the  weight  of  dry  flue  gas 
only.  If  the  moisture  present  in  the  flue  gas  is  to  be  taken  into 
consideration,  a  correction  should  be  made  by  noting  the  hydrogen 
present  in  the  fuel,  the  moisture  in  the  entering  air,  and  the  steam 
used  in  atomization.  In  ordinary  practice  these  factors  are  not 
used,  for,  as  we  shall  see  in  the  discussion  of  the  heat  balance 
in  a  later  chapter,  the  moisture  content  is  properly  cared  for 
under  separate  headings.  Returning  to  our  example,  then,  we 
find  that  the  weight  of  dry  flue  gas  Mg  per  pound  of  fuel  burned 
is 

M  -A  01  en1*  X  0.086  +  3' X  0.09  + 7  X  0.011  +  7X  0.813  _ 
M<~  3(0.086  +  0.011) 

Ratio  of  Air  Drawn  Into  Furnace  to  that  Theoretically  Required. 
We  have  already  derived  sufficient  relationships  to  compute  the 
ratio  of  air  drawn  into  the  furnace  to  that  theoretically  required. 


292  FUEL  OIL  AND  STEAM  ENGINEERING 

Let  us,  however,  proceed  to  the  derivation  of  another  formula 
that  is  recommended  for  use  by  the  American  Society  of  Mechani- 
cal Engineers  in  the  testing  of  boilers. 

Assuming  that  perfect  combustion  is  taking  place  and  neglect- 
ing the  hydrogen  content  of  the  fuel  which  we  know  disappears 
in  the  Orsat  apparatus  before  our  analysis  really  begins,  we  have 

that  for-——  -  Ib.  of  nitrogen  drawn  into  the  furnace     *    4  n  ,_,0, 
cs  Oi    u./ooo 

Ibs.  of  air  must  have  passed  in.     Similarly,  if  no  carbon  monoxide 


is  formed  in  the  flue  gas,  for  -—  Ib.  of  free  oxygen  appearing  in 

O  s 

the  flue  gas,  then  evidently  —  g  —  X  Q  2315  ^*  °^  excess  air  must 

also  have  been  drawn  into  the  furnace.     Hence  we  have  that  the 
total  air  Ma  drawn  in  is  expressed  by  the  formula 


Cs    0.7685 
While  the  air  Mta  theoretically  required  is 


Cs    0.7685         C8    0.2315 

Therefore,  the  ratio  ra  of  the  air  actually  supplied  to  that  theo- 
retically required  may  be  derived  as  follows: 


_  Ma C8     0.7685 

r° ="  Wa ' 


C8    0.7685         Cs    0.2315 


'0.7685  "0.2315 

Since  w4  =  28  and  w2  =  32,  we  have 


32  72      0.7685          F4  -  3.78272 
28          0.2315 

An  Illustrative  Example.  —  Using  the  same  data  as  employed 
in  previous  examples,  we  have 


r    =  > 

0.813  —  3.782X0.09  " 

The  air  theoretically  required  in  this  example  was  computed 
on  page  217  and  found  to  be  12.92  Ib.  Hence  for  the  three  formu- 
las derived  we  arrive  at  the  following  values  for  ra: 


COMBUSTION  DATA  FROM  THE  ORSAT  ANALYSIS     293 

From  formula  (2)  Ma  was  found  to  be  21.1. 

21.1 


12.92 


1.63 


From  formula  (3)  Ma  was  found  to  be  20.7. 

20.7 


12.92 


1.60 


And  from  formula  (4)  Mg  was  found  to  be  20.8.     Hence  M 
is  19.8  and 


It  is  difficult  to  pick  the  most  correct  formula  to  use  in  any 
given   instance.     If  the   analyses   are   obtained   with   precision 


16 
15 
14 
13 
—12 
I" 

!10 

£• 

o"8 
u 

!• 

£   4 
2 

\ 

Analysis  of  Oil 
O          81.52  $ 
H          11.01 
S               .55 
O             6.92 

Grarity-  15°  Ban  me' 
B.  T.U.  per  lb.  -18567 
Flash                 -230°P 

- 

\ 

\ 

\ 

s 

— 

^ 

\ 

a 

^v. 

^ 

— 

^->> 

^, 

"•-* 

^^ 

-^« 

EE 

•  —  ^ 

Assumed:                                  ""* 
Perfect  Combustion 
Ji  1  b.  afro  mf  zing  steam 
per  Ib.of  oil  burned 

0  25  50  75  100 

Per  Cent  Ex.ce.ss  Air 

FIG.  179. — Chart  showing  excess  air  admitted  for  varying  amounts  of  CO2  in 

fuel  oil  practice. 

undoubtedly  results  will  be  obtained  that  will  check  quite  closely, 
indeed  well  within  the  degree  of  precision  of  the  other  factors  that 
enter. 

With  the  combustion  data  thus  obtained,  we  are  now  in  posi- 
tion to  proceed  to  the  determination  of  the  heat  balance  which,  as 
we  shall  see  later,  tells  us  in  detail  just  what  disposition  is  being 
made  of  the  vast  quantities  of  heat  that  are  generated  in  the  fur- 
nace due  to  the  burning  of  the  fuel  oil. 

Combustion  of  one  Pound  of  Oil. — It  is  sometimes  convenient 
to  be  able  to  determine  in  advance  the  maximum  amount  of 


294 


FUEL  OIL  AND  STEAM  ENGINEERING 


CO2  that  can  be  expected  in  the  flue  gas  when  burning  oil  with 
a  given  quantity  of  excess  air.  In  the  following  table  three 
different  cases  of  the  combustion  of  one  pound  of  oil  are  worked 
out,  the  excess  air  being  taken  at  zero  in  the  first  case,  50  per 
cent,  in  the  second  and  100  per  cent,  in  the  third.  In  all  three 
cases  it  is  assumed  that  perfect  combustion  is  obtained,  thus 
eliminating  CO  from  the  calculations  and  that  J/2  1°.  steam  per 
pound  of  oil  is  used  for  atomization.  It  is  also  assumed  that  the 
fuel  oil  contains  82  per  cent.  Carbon  and  11  per  cent.  Hydrogen, 
the  other  ingredients  being  neglected.  The  calculations  do  not 
require  any  explanation,  as  they  can  be  easily  followed,  the  ingre- 
dients of  the  air  and  fuel  being  segregated  and  combined  in 
proper  proportions  according  to  chemical  formulae,  and  then 
converted  from  weight  to  volume,  and  to  per  cent,  by  volume 
as  ordinarily  obtained  in  flue  gas  analysis. 

COMBUSTION  OF  ONE  POUND  OF  OIL 


No 
excess 
air 

50% 
excess 
air 

100% 
excess 
air 

Air  supplied  per  Ib.  oil   

.  .  .Lbs. 

13.21 
3.06 
10.15 
3.06 

0. 
3.00 
0.99 
0.5 
10.15 
14.64 

0. 
24.3 

129.2 
153.5 

0. 
15.8 
84.2 

19.81 
4.59 
15.22 
3.06 

1.53 
3.00 
0.99 
0.5 
15.22 
21.24 

17.1 
24.3 
Neglig 
194.1 
235.5 

7.26 
10.32 

82.42 

26.42 
6.12 
20.30 
3.06 

3.06 
3.00 
0.99 
0.5 
20.30 
27.85 

34.3 
24.3 
ible 
258.5 
317.1 

10.81 
7.66 
81.53 

Oxygen  supplied  per  Ib.  oil  
Nitrogen  supplied  per  Ib.  oil 

.  .  .Lbs. 
.   Lbs. 

Oxygen  used  per  Ib  oil 

Lbs. 

Oxygen     free   . 

Lbs. 

^  CO2  produced  
"bio  H2O  from  combustion  
^  H2O  from  atomizing  steam 

.  .  .Lbs. 
.  .  .Lbs. 
.  .  Lbs. 

o       Nitrogen  supplied 

Lbs. 

"w        Total  weight  of  gases  

...Lbs. 

|       Oxygen  —  Vol.    at    32° 

.  Cu.  ft. 
.Cu.  ft. 
.Cu.  ft. 

0  g  CO2—  Vol.    at   32°  
*o  £  H2O—  Vol.  at  32°  

1  >  Nitrogen—  Vol.     at    32°  
Q       Total    Vol     at    32° 

.Cu.  ft. 
Cu.  ft. 

§  Oxygen  —  Per  cent  by  volume   ... 

COo  —  Per  cent  by  volume  

p^  '  Nitrogen  —  Per  cent,  by  volume  .  . 



CHAPTER  XXXIV 
WEIGHING  THE  WATER  AND  OIL  IN  BOILER  TESTS 

There    are    various    types    of  commercial  water  meters  and 
water  weighers  on  the  market.     Some  of  these  are  quite  accurate 


FIG.  180.  —  An  excellent  design  for  a  measuring  tank. 

for  certain  investigations.     For  boiler  performance,    however, 
they  are  not  to  be  recommended. 


295 


296  FUEL  OIL  AND  STEAM  ENGINEERING 

Volumetric  Method  of  Water  Measurement. — Water  may  also 
be  measured  quantitatively  by  taking  its  volumetric  proportions. 
Its  weight  is  then  computed  after  ascertaining  its  specific  density. 
The  reverse  of  this  principle  is  used,  for  instance,  in  measuring 
the  volumetric  clearance  of  a  steam  engine,  wherein  water  is 
poured  into  the  cylinder  ports  when  the  piston  head  is  at  its 
dead  end  and  the  water  afterwards  drained  out  and  weighed. 
From  the  weight  of  the  water  so  used  the  volume  of  the  clearance 
is  computed.  In  rough  measurements  of  engine  and  boiler  per- 
formance the  water  is  sometimes  measured  by  filling  a  tank  or 
barrel  of  known  volumetric  proportions,  and  by  keeping  account 
of  the  number  of  barrels  so  filled  and  dumped  into  the  sump, 
sufficient  data  is  obtained  to  compute  the  weight. 


FIG.  181. — Platform  scales  and  tanks  for  water  measurement. 

The  boiler  immediately  to  the  right  of  the  platform  scales  is  under  test.  The  tank  below 
the  platform  scales  into  which  the  water  is  emptied  after  being  weighed,  is  utilized  to  fur- 
nish all  water  for  the  boiler  during  the  test.  At  the  beginning  of  the  test  a  hooked  gage 
registers  the  height  of  the  water  in  this  tank,  and  at  each  hourly  period  thereafter  sufficient 
water  is  weighed  and  emptied  into  it  from  the  tanks  above  to  maintain  this  exact  level. 
By  means  of  these  data,  properly  taken,  the  factor  of  evaporation  and  the  boiler  horse- 
power are  easily  computed. 

The  Method  of  Standardized  Platform  Scales. — It  is  now  uni- 
versally recognized,  however,  that  carefully  weighing  the  water 
on  carefully  standardized  scales  is  the  only  safe  and  reliable 
method  of  ascertaining  the  water  fed  to  a  boiler  under  test. 

Let  us  then  see  how  the  details  are  arranged  for  the  weighing 
of  the  water  used  in  steam  generation. 

A  large  square  metallic  tank  about  5  by  5  by  4  ft.  in  dimensions 
is  usually  constructed.  From  the  bottom  of  this  tank  all  feed 
water  for  steam  generation  in  the  boiler  under  test  is  drawn.  At 


WEIGHING  THE  WATER  AND  OIL  IN  BOILER  TESTS  297 

the  beginning  of  the  test  the  water  level  in  this  tank  is  accurately 
measured  by  means  of  a  hook  gage  situated  within  the  tank.  At 
the  end  of  each  hourly  period  of  the  test  and  at  the  conclusion  of 
the  test  this  exact  level  is  also  maintained. 

The  control  for  the  water  supply  is  accomplished  by  two  or 
three  vertical  cylindrical  tanks  that  have  a  conically  shaped  outlet 
at  the  bottom.  These  tanks  are  located  on  standardized  scales 
immediately  above  the  main  supply  tank  that  has  just  been  de- 
scribed. The  complete  installation  is  shown  in  the  illustration. 
At  the  beginning  of  the  test  the  height  of  the  water  in  the  boiler 
is  noted  on  the  gage  glass  in  front  of  the  boiler  and  as  near  as 


FIG.  182. — A  design  for  a  weighing  tank  in  a  boiler  test. 

In  order  to  assure  the  rapid  passage  of  water  or  oil  from  the  tank  upon  the  platform  scales 
into  the  container  below,  the  employment  of  steel  tanks  with  conical  shaped  bottoms  is 
most  effective.  The  outlet  for  the  oil  or  water  should  be  controlled  by  quick-opening  valves. 

is  possible  the  feed  pump  is  regulated  in  its  operation  so  as  to 
maintain  this  level.  At  the  instant  of  conclusion  the  water  level 
is  most  carefully  adjusted  to  meet  the  condition  of  boiler  water 
level  prevailing  at  the  beginning  of  the  test. 

As  the  water  is  drawn  from  the  feed  tanks  beneath  the  platform 
scales  the  operators  fill  the  tanks  on  the  scales  above  and  note 
the  weight  before  and  after  emptying  their  contents  into  the 
tank  below.  Thus  with  ease  the  water  surface  in  the  tank  below 
may  be  kept  at  the  constant  hook  gage  reading  desired,  and  the 
net  weight  of  water  fed  to  the  boiler  ascertained  at  any  time 
during  the  test. 

The  improvised  desk  boards  shown  in  the  illustration  assist 


298 


FUEL  OIL  AND  STEAM  ENGINEERING 


materially  in  aiding  the  water  weighing  operators  to  perform 
their  task  with  ease  and  without  confusion. 

In  order  to  prevent  wastes  and  leakages  of  water,  it  is  well  to 
disconnect  the  outlets  from  the  blowoff  pipes  of  the  boiler  during 
the  period  of  the  test.  All  outlets  from  the  water  columns  and 
gage  glasses  should  also  be  carefully  watched. 

The  Weighing  of  the  Oil. — For  the  careful  weighing  of  the 
oil  fed  to  the  furnace  a  similar  device  is  constructed  as  in  the  case 


SOSff 


OUTLET 

FIG.  183. — An  excellent  water  measurer. 

While  the  automatic  water  measurer  is  not  as  accurate  as  the  standardized  scale  method, 
still  it  finds  many  applications  in  the  testing  laboratory. 

of  the  water  determination.  A  metallic  tank  is  constructed 
from  which  the  oil  supply  is  pumped  to  the  furnace  through  the 
oil  heater.  The  oil  pump  is  best  fitted  with  a  governor  and  an 
automatic  relief  valve.  By  this  means  a  constant  pressure  may 
be  maintained  on  the  oil  line  to  the  burners.  The  discharge  from 
the  relief  valve  is  led  back  to  the  tank  from  which  the  supply  to 


WEIGHING  THE  WATER  AND  OIL  IN  BOILER  TESTS  299 

the  pump  is  taken.  Within  the  tank  is  situated  a  hook  gage,  the 
reading  of  which  is  carefully  ascertained  at  the  instant  of  the 
beginning  of  the  test.  This  exact  reading  is  maintained  through- 
out the  hourly  progress  of  the  test,  and  indeed  at  any  other 
period  if  so  desired. 

This  is  accomplished  by  means  of  a  tank  situated  above  the 
main  supply  tank.  This  tank  is  installed  on  standardized  scales. 
Previous  to  the  discharge  of  the  oil  into  the  tank  below,  the 
scales  are  read  and  when  the  oil  is  brought  to  the  proper  hook 
gage  reading  in  the  tank  below,  the  scales  are  again  read.  By 
subtracting  these  two  readings,  the  net  oil  supply  is  ascertained. 

Sampling  the  Oil  Supply. — As  the  fuel  is  poured  into  the  tank 
upon  the  standardized  scales,  a  dipperful  of  the  oil  is  set  aside 
in  a  convenient  receptacle.  After  a  sample  has  thus  been  ob- 
tained from  each  tank,  as  it  is  weighed,  the  entire  quantity  is  then 
thoroughly  mixed.  Three  parts  of  this  mixture  are  then  put 
into  separate  cans  and  sealed.  One  part  is  analyzed  by  the 
party  or  company  for  whom  the  test  is  being  performed,  the 
second  is  analyzed  by  a  disinterested  party,  and  the  third  is 
retained  in  case  of  disagreement. 

General  Sampling  of  Fuel  Oil  for  Purchase. — The  question  of 
determining  a  proper  sample  for  commercial  valuation  of  oil  is  one 
of  patient  care.  The  United  States  Bureau  of  Mines  has  evolved 
careful  instructions  to  accomplish  this  in  their  technical  paper 
No.  3,  from  which  the  following  is  largely  an  excerpt: 

The  accuracy  of  the  sampling  and,  in  turn,  the  value  of  the 
analysis  must  necessarily  depend  on  the  integrity,  alertness  and 
ability  of  the  person  who  does  the  sampling.  No  matter  how 
honest  the  sampler  may  be,  if  he  lacks  alertness  and  sampling 
ability,  he  may  easily  make  errors  that  will  vitiate  all  subsequent 
work  and  render  the  results  of  tests  and  analyses  utterly  mislead- 
ing. A  sampler  must  be  always  on  the  alert  for  sand,  water  and 
foreign  matter.  He  should  note  any  circumstances  that  appear 
suspicious,  and  should  submit  a  critical  report  on  them,  together 
with  samples  of  the  questioned  oil. 

Sampling  With  a  Dipper. — Immediately  after  the  oil  begins  to 
flow  from  the  wagon  to  the  receiving  tank,  a  small  dipper  holding 
any  definite  quantity,  say  0.5  liter  (about  1  pint),  is  filled  from 
the  stream  of  oil.  Similar  samples  are  taken  at  equal  intervals  of 
time  from  the  beginning  to  the  end  of  the  flow — a  dozen  or  more 
dipperfuls  in  all.  These  samples  are  poured  into  a  clean  drum 


300  FUEL  OIL  AND  STEAM  ENGINEERING 

and  well  shaken.  If  the  oil  is  heavy,  the  dipperfuls  of  oil  may 
be  poured  into  a  clean  pail,  and  thoroughly  stirred.  For  a 
complete  analysis  the  final  sample  should  contain  at  least  4  liters- 
(about  1  gallon).  This  sample  should  be  poured  into  a  clean  can, 
soldered  tight  and  forwarded  to  the  laboratory. 

It  is  important  that  the  dipper  be  filled  with  oil  at  uniform 
intervals  of  time,  and  that  the  dipper  be  always  filled  to  the 
same  level.  The  total  quantity  of  oil  taken  should  represent  a 
definite  quantity  of  oil  delivered  and  the  relation  of  the  sample 
to  the  delivery  should  be  always  stated,  for  instance:  "1-gallon 
sample  representing  1  wagon-load  of  20  barrels." 


FIG.  184. — The  viscosimeter. 

The  design  of  this  viscosimeter  is  based  upon  a  thorough  knowledge  of  lubricating  oils 
and  of  the  requirements  of  manufacture  and  trade.  It  is  made  to  meet  all  demands  as  a 
measure  of  viscosity,  and  is  without  the  many  objections  that  may  be  made  to  all  other  de- 
vices for  this  purpose.  The  viscosity  of  any  oil  is  shown  by  the  number  of  seconds  required 
for  a  certain  number  of  cubic  centimeters  to  run  through  the  open  faucet.  This  corresponds 
to  the  most  generally  approved  standard  now  in  use  by  the  largest  refiners.  (See  page  128.) 

Continuous  Sampling. — Instead  of  taking  samples  with  a 
dipper,  it  may  be  more  convenient  to  take  a  continuous  sample. 
This  may  be  taken  by  allowing  the  oil  to  flow  at  a  constant  and 
uninterrupted  rate  from  a  J^-inch  cock  on  the  underside  of  the 
delivery  pipe  during  the  entire  time  of  discharge.  The  con- 
tinuous sample  should  be  thoroughly  mixed  in  a  clean  drum  or 
pail,  and  at  least  4  liters  (about  1  gallon)  of  it  forwarded  for 
analysis.  A  careful  examination  should  be  made  for  water,  and 
if  the  first  dipperful  shows  water  this  dipperful  should  be 


WEIGHING  THE  WATER  AND  OIL  IN  BOILER  TESTS  301 

thrown  into  the  receiving  tank  and  not  mixed  with  the  sample  for 
analysis. 

Mixed  Samples. — The  all-important  point  is  that  the  gross 
sample,  whatever  the  manner  of  sampling,  shall  be  made  up  of 
equivalent  portions  of  oil  taken  at  regular  intervals  of  time,  so 
that  the  sample  finally  forwarded  for  analysis  will  truly  represent 
the  entire  shipment. 

Water  or  earthy  matter  settles  on  standing.  Hence,  before  a 
large  stationary  tank  or  a  reservoir  is  sampled,  the  character  of 
the  contents  at  the  bottom  should  be  ascertained  by  dredging  with 
a  long-handled  dipper,  and  the  contents  of  the  dipper  should  be 
examined  critically.  If  a  considerable  quantity  of  sediment  is 
brought  up,  it  should  be  cause  for  rejecting  the  oil. 


CHAPTER  XXXV 
MEASUREMENT  OF  STEAM  USED  IN  ATOMIZATION 

As  has  been  previously  set  forth,  there  are  three  methods  used 
in  pulverizing  or  atomizing  the  fuel  oil  in  the  industries  for  heat 
generating  purposes,  namely:  by  compressed  air,  by  steam,  and 
by  some  mechanical  operation. 

In  any  one  of  these  instances  the  actual  expenditure  of  energy 
necessary  to  accomplish  this  result  when  converted  into  heat 
units  should  be  charged  as  a  loss  in  furnace  operation,  when  the 
efficiency  of  the  boiler  as  a  whole  is  being  determined.  And  if 
this  energy  is  taken  from  the  steam  that  is  being  generated  in  the 
boiler,  then  the  net  steam  energy  should  be  computed  by  sub- 
tracting from  the  gross  production  such  steam  as  may  be  used  in 
atomization. 

It  then  becomes  the  task  of  the  steam  engineer  to  construct 
some  accurate  and  convenient  apparatus  whereby  this  may  be 
easily  and  accurately  accomplished. 

There  are  steam  meters  on  the  market  that  may  be  utilized  for 
this  purpose,  and  if  a  careful  design  is  picked,  the  measurement 
may  be  relied  upon.  Many  engineers,  however,  prefer  the  use 
of  a  standardized  orifice  or  the  construction  of  an  apparatus  of 
their  own  whereby  this  important  data  may  be  ascertained  with 
accuracy. 

Mathematical  Expression  for  Flow  of  Steam. — In  the  mathe- 
matical considerations  involved  in  establishing  a  formula  for 
steam  flow  through  -orifices,  a  rather  unique  incident  is 
encountered.  When  the  pressure  of  the  lower  medium  into 
which  the  steam  empties  itself  is  less  than  58  per  cent,  of  the 
higher  pressure,  a  certain  formula  applies.  And  the  rather  re- 
markable thing  is  that  below  this  point  the  flow  is  neither  in- 
creased nor  decreased  by  a  reduction  of  the  external  pressure, 
even  to  the  extent  of  a  perfect  vacuum.  This  was  the  basis  upon 
which  Napier's  formula  was  derived  in  the  chapter  on  Steam 
Calorimetry,  wherein  a  formula  was  given  to  compute  the  steam 
utilized  for  operating  the  calorimeter.  In  this  formula  it  was 

302 


MEASUREMENT  OF  STEAM  USED  IN  ATOMIZATION  303 

seen  that,  if  W  is  the  weight  of  the  steam  in  pounds  per  second 
flowing  into  the  atmosphere,  p  the  absolute  pressure  in  pounds 
per  square  inch  in  the  steam  main,  and  a  the  area  of  orifice,  in 
square  inches,  we  have 

w  =  (i) 


FIG.  185. — Steam  flow  meter  and  draft  gage  on  the  left  with  Venturi  meter 
on  the  right.  This  apparatus  is  at  the  Redondo  Steam  Plant  of  the  Southern 
California  Edison  Company. 

For  steam  flowing  through  an  orifice  from  a  higher  to  a  lower 
pressure  where  the  lower  pressure  is  greater  than  58  per  cent,  of 
the  higher,  we  have  the  formula 

W  ==  1.9  AKV(P-d)d  (2) 

wherein  W  is  the  weight  of  steam  as  discharged  in  pounds  per 
minute,  A  the  area  of  orifice  in  square  inches,  P  the  absolute 
initial  pressure  in  pounds  per  square  inch,  d  the  difference  in 
pressure  between  the  two  sides  in  pounds  per  square  inch,  and  K 


304 


FUEL  OIL  AND  STEAM  ENGINEERING 


is  a  constant  which  has  a  value  of  0.93  for  a  short  pipe  and  0.63  for 
a  hole  in  a  thin  plate  or  a  safety  valve. 

This  latter  formula  is  applicable  in  the  measurement  of  steam 
to  burner  utilized  in  the  atomization  of  fuel  oil.  In  the  following 
lines  a  method  will  be  outlined  setting  forth  the  necessary  appa- 
ratus involved  in  determining  the  variables  in  the  formula. 
Instead  of  actually  substituting  and  solving  numerically,  how- 
ever, it  is  far  simpler  to  construct  a  chart  and  pick  from  this  the 


FIG.  186. — Steam  flow  meter  with  integrating  device  for  registering  total  quantity 

of  steam  passed. 

steam  consumption  for  any  given  steam  pressure  and  pressure 
difference  in  an  orifice  placed  in  the  main. 

Here  then  is  presented  a  ready  and  accurate  means  of  steam 
measurement  for  atomization  purposes.  A  diaphragm  with  an 
orifice  opening  of  0.5  of  a  sq.  in.  in  area  is  inserted  in  the  steam 
line.  On  both  sides  of  this  diaphragm  are  drilled  holes  which 
are  tapped  for  a  J^-inch  pipe.  The  pipes  are  then  connected  to 
both  legs  of  a  manometer  filled  with  mercury.  A  manometer  is 


MEASUREMENT  OF  STEAM  USED  IN  ATOMIZATION  305 

nothing  more  nor  less  than  a  U-tube  filled  with  mercury.  When 
these  two  ends  are  connected  with  pipes  of  varying  pressures, 
the  mercury  in  the  U-tube  will  of  course  be  raised  to  a  higher 
point  in  one  leg  of  the  U-tube  than  in  the  other.  The  difference 
in  this  height  represents  in  inches  of  mercury  the  difference  in 
pressure  between  the  two  sides  of  the  diaphragm.  If  now  a 
steam  gauge  be  inserted  in  the  steam  main  on  the  boiler  side  of 
the  diaphragm,  we  are  enabled  by  means  of  the  atmospheric 
barometer  reading  to  express  these  pressures  in  absolute  pressure 
units  as  set  forth  in  the  chapter  on  pressures.  On  the  burner 


Steam  to  Burneri 


FIG.  187. — Apparatus  employed  in  measuring  steam  in  atomization. 

The  flow  of  steam  through  an  orifice  wherein  a  slightly  lower  pressure  is  maintained  on 
the  further  side  of  the  orifice,  is  found  experimentally  to  be  proportional  to  the  difference 
in  mercury  heights  indicated  on  the  manometer  shown  on  the  right  in  the  illustration.  By 
calibrating  these  readings  prior  to  a  test  the  steam  used  in  atomization  may  be  conveniently 
and  readily  determined  during  a  test. 

side  of  the  steam  main  a  thermometer  is  inserted  as  shown  in  order 
to  measure  the  temperature  of  the  steam  fed  to  the  furnace,  as 
this  steam  in  many  instances  is  superheated  and  hence  the  pres- 
sure reading  does  not  indicate  the  temperature  existing. 

A  manometer  is  accurately  calibrated  prior  to  the  test  by 
allowing  the  steam  to  be  discharged  into  a  barrel  for  a  period  of 
time  under  varying  manometer  readings.  A  curve  is  then  plotted 
similar  to  the  one  shown  in  the  illustration,  which  sets  forth  the 
pounds  of  steam  passing  per  minute  for  any  particular  mano- 
meter reading  in  inches  of  mercury.  If,  then,  readings  are  taken 
20 


306 


FUEL  OIL  AND  STEAM  ENGINEERING 


every  fifteen  minutes  during  the  test,  the  testing  engineer  notes 
at  such  intervals  the  steam  that  has  passed  during  the  preceding 
fifteen-minute  period.  In  such  a  manner  the  total  quantity  of 
steam  used  in  atomization  is  ascertained. 

Thus  in  a  test  at  the  Fruitvale  Station  of  the  Southern  Pa- 
cific Company,  the  pressure  of  the  steam  at  the  burner  was  found 
to  be  168  Ib.  per  sq.  in.  The  temperature  of  the  steam  at  the 
burner  was  440°F.,  which  indicated  a  superheated  condition  of 
65°F.  The  total  steam  used  by  the  burners  for  a  ten-hour  test 


7 
6 

5 


M    3 


0      12345      673      9    10    11    12    13   14    15    16    17    18  19  20 

Pounds  of  Steam  per  Minute 

FIG.  188. — Calibration  of  orifice  for  measurement  of  steam  used  in  atomization. 

Previous  to  a  boiler  test  the  manometer  which  registers  the  pressure  difference  at  the 
faces  of  the  orifice  is  carefully  calibrated  by  condensing  the  steam  flow  and  weighing  the 
hourly  condensate.  These  data  when  plotted  on  a  curve  as  shown  above  enable  the  engi- 
neer to  quickly  ascertain  the  steam  used  in  atomization  at  any  time  during  a  test. 

was  found  by  the  above  means  to  be  7441  Ib.,  while  the  total 
weight  of  water  fed  to  the  boilers  proved  to  be  180,240  Ib.  Hence 
the  percentage  of  total  water  evaporated  by  the  boilers  used 
in  atomization  is  determined  by  dividing  7441  by  180,240,  which 
is  4.16  per  cent. 

The  total  weight  of  oil  fired  was  14,093  Ib.  during  the  test  of 
10  hr.  Hence,  the  pounds  of  steam  utilized  for  atomization  per 
pound  of  oil  fired  is  obtained  by  dividing  7441  by  14,093,  which 
proves  to  be  0.528  Ib. 


CHAPTER  XXXVI 
THE  TAKING  OF  BOILER  TEST  DATA 

In  previous  chapters  we  have  touched  upon  all  the  important 
points  involved  in  tests  on  boiler  economy.  These,  however, 
have  been  considered  under  separate  headings  and  of  necessity 
in  a  somewhat  disconnected  manner.  In  this  and  the  succeeding 
chapters,  we  shall  endeavor  to  link  these  items  into  a  connected 
unit.  This  chapter  will  be  concerned  with  the  gathering  of  the 
data  and  the  next  with  its  computation. 

The  Objects — "What  can  you  do?"  applies  equally  well  to 
the  rating  of  inanimate  objects  as  well  as  to  the  accomplish- 


FIG.   189. — A  portable  pyrometer  outfit. 

For  the  ready  measurement  of  temperatures  in  and  about  the  power  plant,  a  portable  type 
of  pyrometer  is  often  convenient.  In  the  illustration  shown  temperatures  may  be  read  from 
200°F.  to  2200°F.  Such  an  instrument  as  the  one  indicated  is  convenient  in  ascertaining 
the  flue  gas  temperatures  when  the  Orsat  analysis  is  being  taken. 

ment  of  human  endeavor.  And  so  the  object  of  boiler  testing  is 
to  try  out  the  latent  steaming  qualities  of  the  boiler  and  test  its 
strength  both  for  sudden  calls  and  for  endurance.  The  manner 
in  which  the  mechanical  design  of  the  boiler  can  withstand  such 
tests  and  especially  the  efficiency  with  which  it  can  perform  its 
function  of  transforming  the  heat  energy  of  the  fuel  into  energy 
latent  in  the  steam  sent  forth  from  the  boiler  are  as  a  rule  the 
factors  that  either  add  lustre  to  the  name  of  the  manufacturer 
or  else  relegate  the  type  of  steam  generator  under  test  to  the  scrap 
heap. 

307 


308 


FUEL  OIL  AND  STEAM  ENGINEERING 


The  Instruction  for  Boiler  Tests. — The  minute  details  that 
should  be  satisfied  in  order  to  secure  accurate  data  wherewith  to 
rate  the  boiler  and  scientifically  set  forth  its  commercial  worth  are 
elaborately  set  forth  in  instructions  issued  by  the  American 


FIG.  190.— Saybolt  water  indi- 
cator, a  device  whereby  the  water 
contents  of  oil  may  be  conven- 
iently indicated. 


FIG.  191. — An  oil  sampler,  a 
device  which  may  be  easily  low- 
ered into  storage  tanks  of  oil  and 
a  sample  drawn  from  any  par- 
ticular strata  in  the  tank. 


Society  of  Mechanical  Engineers,  compiled  by  their  Committee 
on  Power  Tests.  In  any  case  of  actual  test,  the  steam  engineer 
should  be  provided  with  a  copy  of  these  instructions,  which  he 


THE  TAKING  OF  BOILER  TEST  DATA  309 

can  secure  from  the  secretary  of  the  society  by  the  payment  of  a 
small  fee. 

Since  these  instructions  require  many  pages  wherein  to  set 
forth  the  details  of  a  test,  it  cannot,  of  course,  be  expected  that 
anything  beyond  a  general  outline  of  procedure  in  boiller  testing 
be  set  forth  in  this  article.  Still  it  has  been  the  experience  of 
the  authors  that  if  the  steam  engineer  gets  a  thorough  picture  of 
the  test  details  as  a  whole  he  is  well  equipped,  with  the  assistance 
of  a  nearby  copy  of  the  detailed  instructions,  to  properly  under- 
stand the  procedure. 

The  Test  for  Efficiency  Under  Normal  Rating. — It  has  been 
seen  in  the  chapter  on  Rating  of  Boilers  that  the  manufacturer 
or  builder  rates  the  output  of  the  boiler  on  the  basis  of  the  boiler 
heating  surface  presented  to  the  furnace  gases.  For  each  10 
sq.  ft.  of  boiler  surface  so  exposed  to  the  furnace  gases,  the  boiler 
is  said  to  have  one  boiler  horsepower.  A  test  for  boiler  effi- 
ciency under  this  normal  condition  of  operation  is  one  of  the 
most  important  to  be  ascertained  in  boiler  performance.  In 
order  to  accomplish  this  result,  the  steam  engineer  usually  com- 
putes the  total  weight  of  water  the  boiler  would  approximately 
have  to  evaporate  into  steam  per  hour  under  the  conditions  of 
entering  feed- water  temperature,  boiler  pressure,  and  quality  of 
steam  generated  to  satisfy  the  builder's  rating.  Having  made  a 
careful  estimate  of  this  quantity  he  then  proceeds  to  operate  the 
boiler  as  nearly  as  possible  to  meet  this  condition. 

Time  of  Duration  of  Test. — The  generation  of  steam  is  main- 
tained as  uniformly  as  possible  over  a  period  of  from  8  to  10  hrs. 

The  Beginning  and  Stopping  of  a  Test. — At  the  beginning  of 
the  test  the  level  of  water  in  the  boiler  is  noted  on  the  water 
glass  and  at  the  completion  the  water  is  brought  to  the  same 
height. 

In  the  testing  of  boilers  fired  by  fuel  oil,  the  boiler  is  brought 
up  to  and  continued  at  normal  operating  conditions  until  the 
furnace  wall  and  boiler  room  temperatures  are  at  their  normal 
reading.  Then  the  test  is  started  by  feeding  weighed  water  and 
fuel  oil.  At  the  end  of  the  test,  all  conditions  of  pressure,  tem- 
perature and  rate  of  steam  generation  should  be  as  nearly  as 
possible  the  same  as  at  the  beginning. 

The  Weighing  of  the  Water. — Several  tanks  are  placed  upon 
carefully  calibrated  scales  and  all  water  entering  the  boiler  from 
the  instant  the  test  starts  to  its  closing  point  is  carefully  weighed. 


310  FUEL  OIL  AND  STEAM  ENGINEERING 

The  details  of  the  methods  involved  in  the  weighing  of  water 
have  appeared  in  a  previous  chapter. 

The  Heat  Represented  in  the  Steam  Generated. — The  tem- 
perature of  the  entering  water  and  the  pressure  of  the  steam 
generated  are  noted  at  frequent  intervals.  The  quality  of  the 
steam  as  to  whether  it  is  wet,  dry  saturated,  or  superheated,  is 
also  carefully  determined  quantitatively  by  methods  outlined  in 
previous  chapters. 

With  these  data  at  hand  the  steam  engineer  is  enabled  by  de- 
ductions to  be  set  forth  in  the  chapter  on  Heat  Balance  to  compute 
the  actual  heat  energy  absorbed  by  the  entering  water  in  the 
production  of  steam. 

The  Oil,  Its  Measurement  and  Analysis. — At  the  same  time 
that  the  steam  generating  functions  of  the  boilers  are  being 
ascertained,  it  is  of  course  necessary  to  weigh  the  fuel  oil  ad- 
mitted to  the  furnace  for  firing  purposes  and  to  draw  frequent 
samples  for  the  composite  sample  to  be  used  in  ascertaining  the 
heat  producing  value  of  one  pound  of  fuel.  The  method  of 
weighing  the  oil  and  drawing  the  oil  sample  has  been  set  forth  in  a 
previous  chapter. 

Having  determined  the  calorific  value  of  one  pound  of  fuel 
by  methods  previously  described  the  total  heat  put  into  the  fur- 
nace by  the  fuel  during  the  test  is  computed. 

In  former  chapters  are  to  be  found  discussions  which  fully 
set  forth  the  methods  utilized  in  determining  from  the  oil  sample 
its  calorific  value,  its  moisture  content,  and  its  gravity  under 
standard  conditions  which  are  necessary  to  compute  the  total 
heat  producing  value  of  the  oil  used  in  firing  the  boiler  under 
test. 

The  Steam  Used  in  Atomization. — In  most  central  station 
practice  wherein  fuel  oil  is  consumed  for  heat  generation,  the 
atomization  of  the  fuel  oil  is  accomplished  by  blowing  into  the 
furnace  through  the  oil  burner  a  certain  quantity  of  steam  that  is 
being  generated  in  the  boiler.  To  obtain  the  useful  and  eco- 
nomic quantity  of  steam  generated  by  the  boiler  we  should  then 
subtract  this  steam  used  in  atomization  from  the  total  steam 
generated  in  the  test.  A  practical  method  of  obtaining  experi- 
mentally the  steam  used  in  atomization  has  been  described  in 
Chapter  XXXV. 

The  Boiler  Efficiency. — Having  thus  obtained  the  net  heat 
absorbed  by  the  boiler  under  test  and  also  the  heat  given  out  by 


THE  TAKING  OF  BOILER  TEST  DATA  311 

the  fuel  oil  sprayed  into  the  furnace,  the  ratio  of  the  former  to  the 
latter  gives  us  the  efficiency  of  the  boiler  as  set  forth  in  the  chapter 
on  Heat  Balance. 

In  central  station  practice  on  the  Pacific  Coast  the  gross  boiler 
efficiency  in  the  best  installations  ranges  from  81  to  83  per  cent, 
under  test  conditions.  The  atomization  of  the  steam  lowers  this 
efficiency  by  about  2  per  cent.,  thus  making  the  best  net  boiler 
efficiencies  range  between  79  and  81  per  cent. 

The  Overload  Test. — The  sudden  demand  for  power  during 
certain  hours  of  the  day  make  an  elasticity  in  boiler  steaming 
qualities  absolutely  imperative.  Otherwise,  a  great  additional 
expense  would  be  involved  in  the  cost  and  installation  of  addi- 
tional steaming  units.  Hence  the  overload  steaming  qualities 
of  a  boiler  are  of  utmost  importance,  especially  in  central  station 
or  steam  auxiliary  practice. 

As  an  instance  of  performance  of  a  boiler  under  overload 
conditions  on  the  Pacific  Coast,  an  authentic  case  is  on  record 
where  a  boiler  of  773  rated  horsepower  developed  an  overload 
of  75.7  per  cent,  for  5  hours  and  still  maintained  a  gross  efficiency 
of  80.62  per  cent. 

The  Quick  Steaming  Test. — In  other  instances  the  ability 
of  a  boiler  to  hastily  get  into  action  is  of  prime  importance. 
This  is  especially  true  in  cases  where  boilers  are  held  in  readiness 
for  pumping  station  operation  for  fire  protection.  In  San  Fran- 
cisco, California,  for  instance,  is  located  a  high-pressure  water 
system  whereby  pumps  stand  eternally  ready  to  deliver  12,000 
gal.  of  water  per  minute  to  a  height  of  700  ft.-  should  disaster  by 
fire  ever  again  visit  that  municipality.  The  boilers  that  operate 
the  pumping  station  have  by  test  demonstrated  that  full  boiler 
pressure  and  steaming  conditions  can  be  accomplished  in  less 
than  thirty  minutes  time. 

Again,  other  features  of  test  are  under  special  cases  desirable 
to  attain.  But  the  two  most  important  tests  are  those  of  as- 
certaining the  conversion  ratio  of  heat  represented  in  the  steam 
to  the  heat  supplied  by  the  furnace  under  normal  conditions  of 
operation  and  under  certain  definite  overload  guarantees — in  a 
word,  the  ascertaining  of  boiler  efficiency  for  normal  rating  and 
for  conditions  of  overload. 

Observations  Necessary. — A  complete  tabulated  list  for  final 
test  computation  is  set  forth  in  the  book  of  instructions  previ- 
ously mentioned  as  approved  or  advised  by  the  American  Society 


312  FUEL  OIL  AND  STEAM  ENGINEERING 

of  Mechanical  Engineers.  Let  us  now  look  into  some  of  the 
details  necessary  to  obtain  this  recorded  data. 

In  the  first  place,  one  should  note  on  a  log  sheet  the  general 
observations  such  as  date  of  test,  duration  of  test,  type  of  oil 
burner,  make  of  oil  burner,  number  of  burners  used,  and  with  this 
information  should  be  compiled  sufficient  physical  dimensions 
of  the  boiler  to  enable  one  to  compute  the  builder's  rating  both 
for  the  boiler  and  for  the  superheater.  An  illustration  of  this 
computation  was  set  forth  under  the  chapter  on  Rating  of  Boilers. 

During  the  test  period,  observations  are  usually  taken  every 
fifteen  minutes,  simultaneously  if  possible. 

Pressure  Readings. — The  pressure  of  the  atmosphere  is  read 
in  inches  of  mercury  and  the  steam  gauge  readings  of  the  boiler 
and  superheater  having  been  duly  calibrated  or  corrected  for 
mechanical  inaccuracies,  are  then  reduced  to  absolute  pressure 
readings  as  set  forth  in  the  chapter  on  pressures. 

The  pressure  of  the  oil  under  which  it  is  forced  into  the  furnace 
is  also  usually  noted,  although  it  has  no  bearing  on  data  compu- 
tation. 

The  pressure  of  the  draft  at  various  parts  of  the  ash  pit, 
furnace,  breeching,  and  chimney  are  also  noted  by  means  of  a 
multiple  cock  arrangement  shown  in  Fig.  122.  This  arrange- 
ment makes  possible  the  quick  ascertaining  of  various  draft  read- 
ings by  means  of  one  instrument. 

The  pressure  of  the  saturated  steam  and  also  that  of  the  super- 
heated steam  is  ascertained  by  inserting  carefully  calibrated 
steam  gages,  the  one  in  the  saturated  steam  compartment  and 
the  other  in  the  superheater  compartment.  These  pressures  are 
then  converted  into  absolute  pressure  readings  by  correcting  for 
atmospheric  pressure  as  set  forth  in  Chapter  III. 

Temperature  Readings. — A  thermometer  is  usually  located  in 
the  atmosphere  without  to  ascertain  general  external  tempera- 
ture conditions  of  the  day.  One  is  also  placed  in  the  boiler  room 
to  ascertain  the  temperature  of  the  entering  air  passing  into  the 
furnace. 

To  ascertain  the  temperature  of  entering  feed  waster  and  fuel 
oil,  thermometer  wells  with  thermometers  are  also  installed  at 
nearby  points  of  entrance. 

It  is  often  desirable  to  ascertain  the  temperature  of  the  furnace 
gases  at  various  points  in  their  journey.  To  accomplish  this 
thermo-couples  are  installed  at  the  points  desired  previous  to 


THE  TAKING  OF  BOILER  TEST  DATA  313 

the  firing  of  the  boilers  and  during  the  test  an  electrical  pyro- 
meter is  advised,  especially  if  other  high  temperatures  are  to  be 
taken  in  various  points  of  flue  gas  passage. 

The  Flue  Gas  Analysis. — Simultaneously  with  the  taking  of 
the  temperatures,  pressure  and  other  readings  of  the  test,  the 
flue  gas  analysis  is  ascertained  at  frequent  intervals.  The 
detailed  method  of  taking  these  data  has  been  fully  set  forth  in 
previous  chapters  and  methods  of  computation  of  combustion 
data  explained.  The  Heat  Balance  will  be  set  forth  in  full  in  a 
later  chapter. 

The  Test  as  a  Whole. — The  reader  has  now  before  him  the 
taking  of  the  test  as  a  whole.  At  this  point  he  should  carefully 
review  all  the  previous  chapters  alluded  to  in  this  discussion  so 
as  to  weld  into  a  solid  chain  the  links  that  go  to  make  up  the 
boiler  test  in  fuel  oil  practice. 

Having  thus  in  mind  a  complete  idea  of  the  various  details 
involved  in  the  taking  of  the  boiler  test  data,  we  are  now  in  posi- 
tion to  link  together  the  computed  data  involved  in  formulating 
the  engineer's  report  of  the  economic  results  of  the  test. 


CHAPTER  XXXII 


PRELIMINARY  TABULATION  AND  CALCULATION  OF 
TEST  DATA 

HE  systematic  construction  of  a  log 
sheet  that  will  show  in  the  minutest 
detail  every  incident  in  the  progress 
of  the  boiler  test  is  of  prime  im- 
portance. It  is  far  better  to  overdo 
then  to  underdo  in  the  gathering 
of  detail  data  of  this  kind.  The 
notation  of  remarks  from  time  to 
time  upon  the  log  sheet  concerning 
relevant  observations  during  the 
progress  of  the  test  is  of  much 
service  to  the  engineer  when  he 
finally  comes  to  decide  fine  points 
in  economic  boiler  performance. 

No  straight  and  narrow  schedule 
or  log  sheet  can  be  set  forth  to 
meet  all  types  of  boiler  test.  Each 
particular  test  as  a  rule  involves 
its  own  particular  tabulation.  Let 
us,  however,  consider  a  series  of 
tabulation  sheets  for  boiler  tests  in 

which  oil  is  used  as  a  fuel.  The  suggestions  that  will  be  set  forth 
illustrate  a  carefully  evolutionized  scheme  of  tabulation  for  such 
data  that  may  be  well  followed  in  guiding  one  in  the  construc- 
tion of  his  own  individual  log  form  should  occasion  arise. 

The  Log  Sheet  for  Weighing  the  Water. — In  the  previous 
chapter  we  have  seen  that  the  water  is  brought  to  a  definite 
height  in  the  supply  tank  the  instant  of  starting  the  test.  Above 
this  supply  tank  are  located  standardized  scales  upon  which  the 
water  is  weighed  before  emptying  into  the  supply  tank  below. 
As  a  rule,  at  the  closing  of  each  hourly  period,  water  readings  are 
computed  in  order  that  the  engineer  may  get  a  preliminary 
idea  of  the  progress  of  the  test.  Blank  sheets  are  given  each  water 

314 


FIG.  192. 


TABULATION  AND  CALCULATION  OF  TEST  DATA      315 

weigher,  one  to  be  used  for  each  hourly  period.  Each  sheet  sets 
forth  general  information  indicating  the  kind  of  boiler  under 
test,  the  date  of  test,  the  name  of  the  observer,  and  the  particular 
tank  at  which  each  is  stationed.  A  column  is  devoted  to  the 
number  of  the  scale  reading,  a  second  to  the  gross  weight  of  the 
water  and  tank  before  emptying  into  the  tank  below,  the  tare 
to  be  subtracted  from  the  gross  weight,  which  is  the  weight  of 
the  upper  tank  after  the  water  is  emptied  into  the  tank  below, 
and  a  fourth  column  setting  forth  the  net  weight  or  difference 
of  the  two  preceding  columns.  This  sheet  will  have  somewhat 
the  following  appearance. 


LOG  SHEET  FOR  WATER  FED  TO  BOILER 

Kind  of  boiler 

Method  of  Starting  Test 

Date 

Observers  at  Scales  for  Water . . 


Reading 

Time 

Gross 

Tare 

Net 

Temp,  of       Re- 
water     j    marks 

1 

1. 

2. 

3. 

• 

4. 

5. 

6. 

j 

7. 

8. 

Total- 


— Signature; 


FIG.   193. 


By  using  the  type  of  log  sheet  above  indicated,  it  is  evident  that 
the  engineer  has  a  check  on  his  water  computation,  for  in  the  line 
marked  "total"  the  footing  for  the  gross  weight  should  exactly 
equal  that  for  the  sum  of  the  tare  weight  and  the  net  weight. 


316 


FUEL  OIL  AND  STEAM  ENGINEERING 


A  place  is  also  given  for  a  signature  to  be  appended  by  the  one 
responsible  for  the  weight  notation. 

Log  Sheet  for  the  Fuel  Oil  Fed  to  Furnace. — Simultaneously 
with  the  weighing  of  the  water,  a  similar  log  sheet  is  kept  by 
another  set  of  observers  setting  forth  the  weight  of  fuel  oil  fed 
to  the  furnace.  As  the  weighing  proceeds,  a  periodic  sample  is 
taken  to  make  up  a  composite  sample  for  the  detemination  of  the 
calorific  value  of  the  oil  as  set  forth  in  the  preceding  chapter. 
The  log  sheet  for  the  oil  is  quite  similar  to  that  used  for  the  water 
and  should  be  footed  up  at  the  end  of  each  hourly  period  so  that 
the  engineer  may  have  some  definite  idea  of  preliminary  economic 
results.  A  suggestion  for  this  log  sheet  is  as  follows: 

LOG  SHEET  FOR  OIL  FED  TO  FURNACE 

Type  and  Location  of  Boiler 

Type  of  Burner 

Type  of  Furnace 

Date 

Observers  at  Scales  for  Oil 


Reading 

Time 

Gross 

Tare 

Net 

Temp,  of 
oil 

Re- 
marks 

1. 

2. 

3. 

4. 

5. 

6. 

7. 

8. 

FIG.  194. 


Other  Data  to  be  Taken. — The  tabulation  of  data  to  determine 
the  steam  used  for  atomization  and  the  analysis  of  the  flue  gases 
require  special  treatment,  depending  upon  the  particular  method 
decided  upon  by  the  engineer  to  ascertain  these  factors.  Pre- 


TABULATION  AND  CALCULATION  OF  TEST  DATA      317 


Remarks 

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8.IBX 

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jauanq  •JB  \IQ 

ratures 

pajtsap  -^d  jaq^o  XUB 
»B  aajioq  jo  'draax 

1 

0) 

SIOB^S  jo  -draax 

EH 

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THOOJ  aaij 

JIB  iBuaa^xg 

^TdqsB  ut 
ui  ^jBJp  jo  aoao'j 

ang  ui 
ui  ^JBJP  jo  aojoj 

I 

jaujnq  ^B 

.i.IIiss;ud   [l(  ) 

1 

(a3B9)  pa^Baqaadns 
ajnssajd  uiBa^g 

(a3B3)  pa^BJn^BS 
ajnssajd  uiBa^g 

ja^aniojBq 
ouaqdsora^v 

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»«nx 

O 

SmpBa-a 

- 

N 

CO 

318 


FUEL  OIL  AND  STEAM  ENGINEERING 


vious  chapters  have  already  set  forth  in  detail  suggestions  for  the 
ascertaining  of  these  quantities,  and  the  reader  is  now  advised 
to  re-read  them  in  order  to  correlate  in  his  mind,  as  it  were,  all 
the  data,  that  must  be  taken  in  order  to  ascertain  the  economic 
performance  of  the  modern  boiler  utilizing  crude  petroleum  as  a 
fuel. 


FIG.  196. — The  graphic  log  sheet  for  fuel  oil  tests. 

During  the  progress  of  a  test  a  graphic  plot  most  conveniently  sets  forth  the  behavior 
of  the  variables  under  observation.  The  above  shows  a  typical  graphic  log  sheet  and  its 
method  of  construction  for  fuel  oil  tests. 

The  General  Log  Sheet. — In  addition  to  the  two  log  sheets  just 
described,  a  general  log  sheet  is  necessary  upon  which  to  note 
the  temperatures,  pressures,  flue  gas  analysis  arid  other  informa- 
tion desired. 

Here  is  an  illustration  of  a  suggestion  for  such  a  log  sheet.  At 
the  completion  of  the  test  an  average  is  easily  obtained  for 


TABULATION  AND  CALCULATION  OF  TEST  DATA      319 

the  various  readings  by  footing  up  the  total  and  dividing  by  the 
number  of  readings  noted.  The  columns  for  the  water  fed  to  the 
boiler  and  the  oil  fed  to  the  furnace  are  footed  and  as  in  the  hourly 
sheets  previously  described,  the  totals  from  these  sheets  which 
are  noted  on  this  general  log  sheet  should  now  check — that  is, 
the  total  gross  should  equal  the  sum  of  the  total  tare  and  total 
net  columns.  The  reader  is  to  bear  in  mind  that  the  actual  no- 
tations to  be  made  in  any  particular  test  are  not  all  set  down  in 
this  general  log  sheet  suggestion,  for  the  information  desired 
and  the  purpose  of  the  test  must  in  each  given  case  determine 
these  factors.  The  sheet  will,  however,  serve  as  a  general  guide 
for  such  matters. 

The  Plotting  of  Test  Data. — As  the  test  proceeds  hour  by  hour, 
it  is  very  instructive  and  helpful  to  keep  a  diagrammatic  log  sheet 
also.  By  this  means  a  glance  will  often  reveal  certain  irregu- 
larities that  may  be  righted  at  their  incipiency.  Such  a  log  sheet 
is  shown  in  Fig.  196  and  by  reference  to  it  the  reader  will  ob- 
serve how  the  history  of  a  test  may  be  simply  and  clearly  set 
forth. 


CHAPTER  XXXVIII 
THE  HEAT  BALANCE  AND  BOILER  EFFICIENCY 

The  steaming  qualities  of  a  boiler  are  best  set  forth  by  measur- 
ing its  so-called  efficiency.  The  efficiency  of  a  boiler  is  the 
relationship  between  the  heat  absorbed  per  pound  of  fuel  fired 
and  the  calorific  value  of  1  Ib.  of  fuel.  Thus  although  each 
pound  of  fuel  consumed  in  steam  production  is  found  to  have 
a  calorific  value  of  19,450  B.t.u.  in  the  numerical  illustration 
for  this  chapter,  that  portion  alone  of  this  heat  which  is  actually 
represented  in  the  steam  itself  is  of  economic  value. 

In  the  illustrative  test  which  is  made  use  of  throughout  this 
chapter,  it  will  be  found  that  of  this  19,450  B.t.u.  represented  in 
each  pound  of  oil  only  14,076.56  go  toward  power  generation. 
It  is  then  useful  and  instructive  to  analyze  the  losses  in  a  boiler 
and  see  through  what  channels  this  heat  has  been  dissipated. 
The  major  portion  of  these  losses  may  be  easily  computed  by 
means  of  data  taken  in  the  test.  Those  which  cannot  be  mathe- 
matically computed  are  thrown  under  the  column  entitled  "  Stray 
Losses,"  and  are  made  to  represent  such  an  amount  that  the  total 
losses  together  with  the  useful  heat  generated  in  the  boiler 
represent  the  heat  from  1  Ib.  of  fuel. 

Let  us  then  examine  the  various  channels  of  heat  transfer 
going  on  in  the  boiler  and  see  how  the  details  of  the  heat  balance 
are  set  forth.  In  this  discussion  H0  will  represent  the  calorific 
value  of  1  Ib.  of  fuel  oil  under  test. 

(a)  a.  The  Total  Heat  Absorbed  by  the  Boiler. — As  has  been 
previously  shown,  the  equivalent  evaporation  of  a  boiler  per 
pound  of  oil  represents  the  number  of  pounds  of  water  which 
would  be  evaporated  into  steam  per  pound  of  oil  if  the  water  was 
at  212°F.  and  under  atmospheric  pressure,  and  this  water  then 
converted  into  dry  saturated  steam  at  the  same  temperature  and 
pressure.  It  is  self-evident  then  that  the  total  heat  absorbed  by 
the  boiler  for  each  pound  of  oil  burned  in  the  furnace  is  equal  to 
the  equivalent  evaporation  multiplied  by  the  heat  necessary  to 
convert  1  Ib.  of  water  into  steam  under  conditions  just  mentioned. 

320 


THE  HEAT  BALANCE  AND  BOILER  EFFICIENCY       321 

This  quantity  of  heat  has  been  found  by  Marks  and  Davis  to  be 
970.4  B.t.u.,  as  set  forth  in  previous  discussions.  Representing 
this  in  a  formula  the  total  heat  Ht  absorbed  by  the  boiler  per 
pound  of  fuel  is 

Ht  =  Me  X  Le  (1) 

in  which  Ht  is  the  total  heat  absorbed  by  the  boiler  per  pound  of 
dry  fuel,  Me  the  equivalent  evaporation  per  pound  of  oil,  and 
Lc  the  latent  heat  of  evaporation  at  212°F.,  which  is  970.4  B.t.u. 
Hence,  if  the  equivalent  evaporation  of  a  boiler  is  found  by  test 
to  be  28,225  Ib.  of  water  per  hour,  and  if  the  measurement  of 
oil  shows  that  1872  Ib.  of  oil  have  been  consumed 

M    _  28,225 

'T872 


14,639 

b.  Heat  Absorbed  by  Boiler  for  Atomization.  —  In  ordinary 
practice  of  fuel  oil  combustion,  there  are  three  methods  of 
atomization  employed.  In  the  larger  power  plants  the  use  of 
steam  for  atomization  purposes,  or  in  other  words,  the  diverting 
of  steam  from  the  boiler  into  the  furnace  in  order  to  atomize  the 
oils,  seems  to  have  by  far  the  preference.  It  is  proposed  to  alter 
the  rules  of  the  American  Society  of  Mechanical  Engineers  so 
that  the  heat  represented  by  the  steam  used  in  atomization 
must  be  subtracted  from  the  total  heat  absorbed  by  the  boiler 
in  order  to  compute  the  net  evaporative  power  of  the  boiler. 
Hence  to  make  this  computation  we  must  know  the  number  of 
pounds  of  steam  used  in  atomization  per  pound  of  oil  burned. 
Methods  of  arriving  at  this  result  have  been  described  in 
Chapter  XXXV. 

Calling  M8  the  pounds  of  steam  used  in  atomization  per  pound 
of  fuel  burned,  Hs  the  total  heat  per  pound  of  steam  so  used,  and 
hi  the  heat  in  the  entering  feed  water,  and  Ha  the  heat  absorbed 
by  the  boiler  per  pound  of  fuel  in  atomizing  the  oil,  it  is  evident 
that 

Ha  =  M8(Ha  -  hi)  (2) 

Thus  it  has  been  found  in  the  test  under  description  that  0.530 
Ib.  of  steam  were  utilized  in  atomization  per  pound  of  oil.  Satu- 
rated steam  at  a  temperature  of  381.9°  was  used.  From  the 
steam  tables  such  steam  is  found  to  have  a  total  heat  of  1198.08 

21 


322  FUEL  OIL  AND  STEAM  ENGINEERING 

B.t.u.  The  entering  feed  water  was  at  a  temperature  of  169. 1°F. 
and  has  a  heat  of  liquid  amounting  to  136.87  B.t.u.  We  find 
by  substitution  that  the  heat  absorbed  in  atomizing  the  oil  is 
computed  as  follows: 

Ha  =  0.530  (1198.98  -  136.87)  =  562.44  B.t.u. 

c.  Net  Heat  Absorbed   by  Boiler  for  Power   Generation. — 

Since  then  the  heat  utilized  in  atomization  must  be  subtracted 
from  the  total  heat  absorbed  by  the  boiler,  to  ascertain  the  net 
heat  Hn  absorbed  by  the  boiler  for  power  generation,  we  have 
the  following  formula : 

Hn  =  Ht  -  Ha  (3) 

:.Hn  =  14,639  -  562.44  =  14,076.56  B.t.u. 

(6)  Loss  Due  to  Water  in  the  Fuel. — All  fuels  contain  a  certain 
amount  of  moisture.  It  is  evident  that  since  it  requires  con- 
siderable heat  to  convert  this  moisture  into  steam  and  then  to 
send  it  forth  from  the  chimney  in  a  superheated  condition,  a 
definite  loss  is  thereby  sustained  in  boiler  operation.  This 
moisture  must  first  be  raised  to  212°F.,  then  converted  into 
steam,  and  then  heated  to  the  temperature  of  the  outgoing 
chimney  gases.  If  we  let  Mw  be  the  proportion  by  weight  of 
moisture  in  the  1  Ib.  of  fuel,  t0  the  temperature  of  the  oil  entering 
the  burner,  tg  the  temperature  of  the  escaping  gases,  and  Hm  the 
loss  due  to  moisture  in  the  fuel  per  pound  of  fuel  burned,  we  may 
write  at  once  an  equation  representing  this  loss. 

Thus 

Hm  =  Mw  [212  -  t0  +  970.4  +  0.47  ft  -  212)]  (4) 

The  reasons  for  this  formula  are  seen  by  inspection.  To  raise 
each  pound  of  moisture  from  t0  to  212°  F.  would  require  as  many 
B.t.u.  as  the  raise  in  temperature,  in  other  words  (212  —  t0) 
B.t.u.  Again,  to  evaporate  each  pound  would  require  970.4 
B.t.u.,  and  as  0.47  of  a  B.t.u.  are  required  to  superheat  1  Ib.  of 
steam  1°  in  temperature  at  atmospheric  pressure,  each  pound  of 
steam  superheated  to  the  temperature  of  the  outgoing  chimney 
gases  would  require  0.47  ft  -  212)  B.t.u.  Therefore,  the  total 
heat  required  for  Mw  pounds  would  be  as  indicated  in  the  formula 
above  by  summing  up  these  separate  components. 

Thus  in  the  test  under  consideration,  let  us  assume  that  the 
fuel  contains  1  per  cent,  of  moisture;  that  its  entering  temperature 


THE  HEAT  BALANCE  AND  BOILER  EFFICIENCY       323 

is  96°F.,  and  that  the  temperature  of  the  escaping  gases  is  400°F. 
Hence 

Hm  =  0.01  [212  -  96  +  970.4  +  0.47  (400  -  212)]  =  11.67 

B.t.u. 

(c)  Loss   Due    to    Water   Formed  by  Burning  Hydrogen.  — 

In  the  chapter  on  chimney  gas  analysis,  it  was  seen  that  the 
Orsat  Apparatus  is  so  constructed  that  the  vapor  or  superheated 
steam  formed  by  the  burning  of  the  hydrogen  content  in  the  fuel 
is  condensed  into  water  upon  entering  the  burette;  hence  the 
Orsat  analysis  indicates  only  dry  flue  gases  and  takes  no  account 
of  the  percentage  of  steam  actually  present  in  these  gases.  It  is 
seen  then  that  the  moisture  formed  by  the  burning  of  hydrogen 
must  also  create  a  loss  as  it  journeys  upward  through  the  boiler. 
Assuming  Hh  to  be  the  heat  lost  due  to  the  moisture  formed  by  the 
burning  of  hydrogen  by  following  identically  similar  processes 
of  reasoning  just  employed  in  the  considerations  of  the  loss  due 
to  the  moisture  in  the  fuel,  we  find  that  each  pound  of  moisture 
formed  by  the  burning  of  hydrogen  requires 

[212  -t0+  970.4  +  0.47  (ta  -  212)]  B.t.u. 

From  the  principles  of  chemistry  each  pound  of  hydrogen  com- 
bines with  8  Ib.  of  oxygen,  thereby  forming  9  Ib.  of  water  or  steam. 
This  relationship  gives  us  a  ready  means  of  computing  the  weight 
of  water  vapor  formed  by  the  burning  of  hydrogen,  although  the 
Orsat  analysis  failed  to  do  so.  Assuming  Mh  to  be  the  propor- 
tion by  weight  of  hydrogen  per  pound  of  fuel  oil  burned,  we  have 


Hh  =  9Mh  [212  -  t0  +  970.4  +  0.47  (ta  -  212)]  (5) 

By  referring  to  the  test  data,  we  find  that  the  fuel  analysis 
shows  0.11  Ib.  of  hydrogen  per  pound  of  fuel,  that  the  tempera- 
ture of  entering  air  is  84°  and  the  temperature  of  the  escaping 
gases  400°,  therefore 

Hh  =  9  X  0.11  [212  -  84  +  970.4  +  0.47  (400  -  212)]  = 
1166.97  B.t.u. 

(d)  Loss  Due  to  Heat  Carried  away  by  Dry  Gases.  —  From 
the  Orsat  analysis,  as  was  seen  in  Chapter  XXXIII  on  the  Compu- 
tation of  Combustion  Data,  the  pounds  of  dry  gas  passing  up  the 
chimney  per  pound  of  fuel  burned  may  be  easily  computed  by 
means  of  several  different  formulas.  It  is  found  by  experiment 


324  FUEL  OIL  AND  STEAM  ENGINEERING 

that  it  requires  0.24  B.t.u.  to  raise  one  pound  of  chimney  gas 
1°  in  temperature.  Hence  if  Mg  be  the  pounds  of  dry  chimney 
gas  per  pound  of  fuel,  the  total  heat  wasted  Hg  in  raising  the 
temperature  of  these  dry  gases  is  seen  to  be 

Hg  =  0.24  (tg  -  ta)Mg  (6) 

In  this  particular  instance,  let  us  assume  that  by  the  applica- 
tion of  our  formula  we  find  that  19.83  Ib.  of  dry  chimney  gas  are 
formed  per  pound  of  fuel  burned;  that  the  temperature  of  the 
entering  air  is  84°,  and  that  of  the  outgoing  chimney  gases  400°. 
Hence 

Htt  =  0.24  (400  -  84)  19.83  =  1503.91  B.t.u. 

(e)  Loss  Due  to  Carbon  Monoxide. — In  the  burning  of  every 
pound  of  carbon  to  carbon  dioxide,  14,600  B.t.u.  are  liberated. 
When  the  carbon  is  not  completely  burned  but  passes  up  the 
chimney  in  the  form  of  carbon  monoxide  only  4450  B.t.u.  per  Ib. 
of  carbon  so  burned  are  liberated.  Hence  whenever  carbon 
monoxide  appears  in  the  gas  analysis  it  is  evident  that  a  definite 
loss  is  being  sustained  due  to  this  incomplete  combustion  of  the 
carbon. 

For  every  pound  of  carbon  which  passes  up  the  chimney  as 
carbon  monoxide,  a  net  loss  of  10,150  B.t.u.  are  thus  uselessly 
thrown  away.  Let  us  assume  that  1  Ib.  of  carbon  volumetrically 
produces  V\  units  by  volume  of  carbon  dioxide  and  V$  units  by 
volume  of  carbon  monoxide.  If  this  is  true  it  is  evident  that  in 

V8 
every  pound  of  carbon  so  burned  y     \    y   pounds  are  converted 

into  carbon  monoxide,  which  represents  a  loss  of  10,150  B.t.u. 
per  pound.  Hence  if  there  are  C  units  of  carbon  by  weight  in 
each  pound  of  the  fuel,  the  formula  to  be  applied  to  ascertain 
the  loss  due  to  incomplete  combustion  Hc  is 

Hc  =  Oy^ryr  X  10,150  (7) 

In  the  particular  case  cited  above  the  fuel  has  0.86  proportions 
by  weight  of  carbon  and  0.01  proportions  by  volume  go  out  of  the 
chimney  in  the  form  of  carbon  monoxide  and  0.0979  proportions 
by  volume  in  the  form  of  carbon  dioxide.  Then  the  total  loss 
is  evidently 

10,150X0.01 
Hc  =  V^  =  8°L82  B't'U- 


THE  HEAT  BALANCE  AND  BOILER  EFFICIENCY       325 

(/)  a.  Loss  Due  to  Generating  Steam  for  Atomization. — By 

referring  back  to  (a)  b  in  this  discussion,  we  find  that  the  loss 
due  to  generating  steam  used  in  atomization  is  represented  by 
the  formula 

Ha  =  M8  (H8  -  hd  (8) 

and  in  the  particular  instance  in  question  it  is  562.44  B.t.u. 
per  pound  of  fuel  burned.  Where  the  steam  used  in  atomization 
is  brought  from  an  outside  source,  it  would,  of  course,  be  neces- 
sary to  neglect  the  correction  made  under  (a)  b,  although  the 
quantity  under  this  heading  must  still  be  taken  into  account. 

b.  Loss  Due  to  Superheating  Steam  used  for  Atomization. — 
If  the  steam  has  been  injected  into  the  furnace  in  atomization, 
it  is  clearly  evident  that  for  every  pound  so  injected,  0.47  of  a 
B.t.u.  are  required  in  superheating  it  to  the  temperature  of  the 
outgoing  chimney  gases.     Hence  the  loss  so  sustained  is  seen 
at  once  to  be  computed  from  the  formula : 

Hsa  =  OA7MS  (ttt  -  t8)  (9) 

in  which  Hsa  is  the  loss  due  to  superheating  steam  due  to  atomiza- 
tion per  pound  of  fuel  burned;  M8  is  the  proportion  by  weight 
of  steam  used  in  atomization  per  pound  of  oil;  tg  the  temperature 
of  escaping  flue  gas;  and  ts  the  temperature  of  steam  used  in 
atomization. 

Since  we  have  found  that  0.53  Ib.  of  steam  were  used  per  pound 
of  oil  in  atomization  and  the  temperature  of  the  outgoing  chimney 
gases  was  400°,  and  that  of  the  inlet  temperature  of  the  steam 
381.9°,  we  see  at  once  that 

Hsa  =  0.47  X  0.53(400  -  381.9)  =4.51  B.t.u.  per  Ib.  of  oil 

burned. 

c.  Total  Loss  in  Atomization. — If  now  the  steam  supply  in 
atomization  is  taken  from  the  boiler  under  test,  or  even  brought 
from   a  separate  supply,  it  is  clear  that  the  total  loss  so  sus- 
tained is  the  sum  of  Ha  and  Hsa.     Hence  the  total  loss  Hta  in 
atomization  is 

Hta  =  Ha  +  HM  (10) 

In  the  case  at  issue  then, 

H8a  =  562.44  +  4.51  =  566.95  B.t.u. 


326  FUEL  OIL  AND  STEAM  ENGINEERING 

(gf)  Loss  Due  to  Moisture  in  Entering  Air. — All  air  drawn  into 
a  furnace  holds  in  suspension  a  certain  amount  of  moisture. 
In  previous  instances  of  moisture  entering  the  flue  gas  it  is  seen 
that  a  loss  is  sustained  in  superheating  this  moisture  content  to 
the  temperature  of  the  outgoing  chimney  gases.  Let  Ma  be  the 
pounds  of  air  that  enter  the  furnace  per  pound  of  fuel  burned,  and 
let  K  be  the  proportion  by  weight  of  moisture  in  this  entering 
air  then  the  loss  in  heat  units  Hma  due  to  this  moisture  may  be 
expressed  at  once  by  the  formula 

Hma  =  0.47  MaK  (tg  -  ta}  (11) 

In  the  illustration  cited  in  this  case  it  was  found  that  there  were 
22.82  Ib.  of  chimney  gas  formed,  which  means  that  21.82  Ib.  of 
air  were  drawn  into  the  furnace  to  burn  1  Ib.  of  fuel  oil;  that 
the  entering  moisture  represented  0.75  per  cent,  of  the  enter- 
ing air  which  found  its  way  into  the  furnace  at  a  temperature 
of  84°  and  escaped  from  the  chimney  at  a  temperature  of  400°. 

Therefore 

Hma  =  0.47  (21.82)  X  0.0075  (400  -  84)  =  23.18  B  t.u. 

(h)  Stray  Losses. — In  order  to  make  a  perfect  balance  between 
all  of  the  various  factors  entering  a  heat  balance,  the  residual 
heat  of  each  pound  of  oil  not  otherwise  accounted  for  is  thrown 
into  a  column  headed  •"  Stray  Losses.''  It  is  clearly  evident 
that  this  loss  is  equal  to  the  calorific  value  of  the  fuel  per  pound 
less  the  sum  of  all  the  heat  accounted  for  in  the  various  columns 
cited  above.  Hence  if  Hs  represents  the  stray  losses  per  pound 
of  fuel,  and  H0  the  calorific  value  of  1  Ib.  of  fuel  oil  under  test, 
we  may  write  the  formula  as  follows: 

Hs    =    Ho   -.(#»'  +   Hm   +   Hh  -f   Hg   +  Hc   +   Hta   +  Hma)       (12) 

and  in  the  case  at  issue  by  summarizing  the  columns  we  find  this 
to  be  18151.06  B.t.u. 

.'.Hs  =  19,450  -  18,151.06  =  1,298.94  B.t.u. 

(i)  Total  Calorific  Value  or  Summary. — We  are  now  in  a 
position  to  summarize  the  complete  heat  balance.  The  various 
items  just  discussed  will  be  seen  to  be  represented  both  in  B.t.u. 
per  pound  and  in  percentages,  as  follows: 


THE  HEAT  BALANCE  AND  BOILER  EFFICIENCY       327 
SUMMARY  FOR  HEAT  BALANCE 


Loss 

es 

Heat 
avail- 

B.t.u. 

percent. 

able 

Total  B.t.u.  in  1  pound  water  free  oil  

19,450 

(a)  a.  In    total    heat    absorbed    by 

boiler                                        14  639  00 

b.  Heat    absorbed    for    atomiza- 

tion  562  44 

c.  Net  heat  absorbed  for  power  

14,076.56 

72.37 

(6)  Loss  due  to  moisture  in  fuel  

11.67 

0.06 

(c)  Loss  due  to  moisture  of  burning  H 

1,166.97 

6.00 

(d)  Loss  due  to  heat  carried  away  by  gases  .... 

1,503.91 

7.73 

(e)  Loss  due  to  incomplete  combustion  of  C  .  .  . 

801.82 

4.12 

(/)  a.  Loss     due     to    generation     of 

steam  for  atomization  562  .  44 

b.  Loss    due    to    superheating   of 

steam  for  atomization  4.51 

c.   Total  loss  due  to  atomization  

566.95 

2.92 

(</)  Loss  due  to  moisture  of  entering  air 

23.  18 

0.  12 

(h)  Stray  losses  

1,298.94 

6.68 

19,450.00 

100.00 

19,450 

The  Net  Boiler  Efficiency. — In  fuel  oil  central  station  practice, 
due  to  the  fact  that  a  portion  of  the  steam  generated  in  the  boiler 
is  used  for  atomization,  we  need  further  definition  for  true  boiler 
efficiency  than  the  notation  set  forth  in  the  Rules  for  Boiler 
Tests  advised  by  the  Power  Test  Committee  of  the  American 
Society  of  Mechanical  Engineers.  Further  comment  on  this 
point  will  be  made  in  the  next  chapter.  Suffice  it  to  say  here, 
however,  that  the  net  boiler  efficiency  Bne  for  the  boiler  will  be 
considered  as  that  resulting  from  taking  the  ratio  of  the  heat  Hn 
represented  in  the  useful  steam  evaporated  by  the  boiler  per 
pound  of  oil  fired  to  the  total  heat  H0  given  out  by  each  pound 
of  oil  burned. 

Thus 


(13) 


328  FUEL  OIL  AND  STEAM  ENGINEERING 

In  the  data  set  forth  in  the  heat  balance  j  ust  computed  we  find 
then  that 

14,076.56       ,__  0 
*~  =    -19450-     =  72'3 

The  Boiler  Efficiency  as  a  Steaming  Mechanism.  —  In  case, 
however,  it  is  desired  to  ascertain  the  boiler  efficiency  Be  as  a 
steaming  mechanism,  it  would  then  of  course  be  proper  to  compute 
this  boiler  efficiency  Be  by  taking  the  ratio  of  the  total  heat  Ht 
absorbed  by  the  steam  for  each  pound  of  oil  fired  to  the  total 
heat  H0  actually  given  out  by  each  pound  of  fuel  oil  fired.  Thus 

Be  =  fi  (14) 

Jtlo 

Under  such  a  definition  the  boiler  data  set  forth  in  the  heat 
balance  would  indicate  a  boiler  efficiency,  thus 


The  data  from  which  the  heat  balance  and  boiler  efficiency 
illustration  was  computed  in  this  chapter  is  summarized  as 
follows  : 

SUMMARY  OF  DATA  USED 

Calorific  value  of  dry  fuel  oil  per  pound  ........  ..........  19,450  B.t.u. 

Equivalent  evaporation  of  water  per  hour  .................  28,225  Ib. 

Consumption  of  dry  fuel  oil  per  hour  .....................  1,872  Ib. 

Steam  used  in  atomization  per  Ib.  of  dry  fuel  oil  ...........  0.  520  Ib 

Temp,  of  saturated  steam  used  in  atomization  .............  381  .  9°F.  ' 

Temp,  of  feed  water  ...................................  169  .  1°F. 

Per  cent,  of  moisture  in  fuel  oil  ..........................  1.0% 

Temp,  of  entering  fuel  oil  ...............................  96°F. 

Temp,  of  flue  gases  ....................................  400°F. 

Hydrogen  content  of  fuel  ...............................  11.0% 

,Carbon  content  of  fuel  .................................  86  % 

Temp,  of  entering  air  ..................................  84°F. 

Weight  of  dry  chimney  gases  per  Ib.  of  dry  fuel  ............  19  .  83  Ib. 

Weight  of  entering  air  per  Ib.  of  dry  fuel  oil  ...............  21  .  82  Ib. 

Carbon  dioxide  in  flue  gas  ..............................  9  .  79% 

Carbon  monoxide  in  flue  gas  ............................  1  .  00% 

Moisture  of  entering  air  from  boiler  room  .................  0.  75% 


CHAPTER  XXXIX 

SUMMARY  OF  SUGGESTIONS  FOR  FUEL  OIL  TESTS  AND 
THEIR  TABULATION 

The  rules  for  conducting  boiler  performances,  as  advised  by 
the  Power  Test  Committee  of  the  American  Society  of  Mechan- 
ical Engineers,  covers  in  wonderful  detail  the  setting  forth  of 
apparatus  and  tabulation  of  data  for  such  performances,  when 
coal  is  employed  as  a  fuel.  Only  brief  mention  is,  however,  made 
for  alterations  necessary  when  crude  petroleum  is  used  as  a  fuel. 
Since  a  greater  number  of  engineers  would  probably  be  incon- 
venienced than  those  actually  benefited  by  attempting  to  make 
a  set  of  rules  broad  enough  to  cover  both  performances  by  coal 
and  by  oil  as  fuels,  an  appendix  should  be  drawn  up  to  satisfy 
standardized  conditions  of  test  for  oil  fired  boilers.  This  lack 
of  standardized  performance  has  caused  considerable  confusion 
in  those  communities  where  oil  is  used  as  a  fuel. 

The  most  glaring  source  of  confusion  is  that  relating  to  boiler 
efficiency.  Some  engineers  maintain  that  boiler  efficiency  is 
the  ratio  of  heat  actually  transferred  from  the  fuel  through  the 
metallic  parts  of  the  boiler  to  the  total  quantity  of  heat  given  out 
by  the  fuel.  When  coal  is  used  as  a  fuel  this  definition  is  per- 
fectly proper,  but  when  oil  is  the  fuel  employed  confusion  is 
at  once  introduced,  due  to  the  fact  that  as  a  rule  a  certain  amount 
of  the  steam  generated  must  be  utilized  to  atomize  the  oil  in  the 
furnace.  In  the  last  chapter  it  was  shown  that  the  efficiency 
of  an  oil  fired  boiler  computed  on  one  assumption  in  a  specific 
instance  is  75.27  per  cent.,  and  on  another  assumption  it  becomes 
but  72.37  per  cent. 

Let  us  then  discuss  some  of  the  points  wherein  additional 
instructions  are  desirable  to  properly  conduct  boiler  tests  where 
oil  is  used  as  the  fuel  for  heat  production. 

Efficiency  for  Oil  Fired  Boilers  Defined. — Perhaps  the  most 
important  point  is  to  come  to  some  definite  decision  relative  to 
an  exact  manner  of  arriving  at  the  efficiency  of  the  boiler  as 
above  alluded  to.  In  this  work  we  shall  consider  that  the  true 

329 


330 


FUEL  OIL  AND  STEAM  ENGINEERING 


FUEL  OIL  TESTS  AND  THEIR  TABULATION 


331 


332  FUEL  OIL  AND  STEAM  ENGINEERING 

efficiency  of  the  boiler  and  furnace  is  to  be  found  by  taking  the 
ratio  of  the  heat  represented  in  the  steam  after  deducting  the 
heat  used  for  atomization  purposes  to'  the  total  quantity  of  heat 
given  out  by  the  fuel,  as  set  forth  in  the  last  chapter.  On  the 
other  hand  to  compute  the  efficiency  of  the  boiler  as  a  steam 
producing  agent,  we  shall  take  the  ratio  of  the  heat  of  all  steam 
generated  in  the  boiler  for  a  given  consumption  of  fuel  to  the 
total  heat  given  out  by  the  fuel.  The  efficiency  of  a  boiler 
and  furnace  is  as  a  rule  reduced  from  2  to  5  per  cent,  below  the 
boiler  efficiency  as  a  steam  producing  agent,  as  shown  in  the 
previous  paragraph. 

Code  for  Testing  Oil  Fired  Boilers. — Upon  invitation  of  the 
Power  Test  Committee  of  the  American  Society  of  Mechanical 
Engineers,  the  authprs  of  this  work  have  presented  proposals  to 
the  Society  to  meet  this  growing  need  in  standardization. 

These  proposals  have  been  embodied  in  two  tables  of  Fuel 
Oil  Test  Data  made  up  as  nearly  as  possible  to  correspond  with 
the  Code  of  1915  for  boiler  tests,  as  published  in  Volume  37  of 
the  Transactions  of  the  Society.  Table  1 :  Data  and  Results  of 
Evaporation  Test  is  reproduced  on  the  following  pages  333  to 
336,  and  Table  2:  Principal  Data  and  Results  of  Boiler  Test, 
is  reproduced  on  page  336. 

In  these  tables  the  item  numbers  have  been  retained  as  far 
as  possible  to  correspond  with  the  item  numbers  in  the  code  of 
1915.  The  principal  changes  consist  in  the  following:  The  omis- 
sion of  reference  to  grates  and  grate  surface  and  substituting 
therefor  the  number  of  oil  burners  and  dimensions  of  furnace; 
the  omission  of  reference  to  ash,  combustible,  firing  data,  etc., 
but  introducing  instead  items  connected  with  the  steam  used  for 
atomizing  the  oil  at  the  burner.  The  term  "net  efficiency" 
is  also  introduced,  by  which  is  meant  the  efficiency  of  the  boiler 
as  discussed  on  page  327. 

In  addition  to  the  tabulations  submitted,  the  writers  have 
suggested  that  the  appendix  in  the  Code  Rules  be  amplified  so 
as  to  include  a  description  of  methods  for  obtaining  gravity  of 
oils,  flash  point,  the  water  content  and  the  viscosity.  These 
determinations  should  be  fully  described  and  included  in  Appen- 
dix No.  14,  of  the  Report  of  the  Power  Test  Committee  begin- 
ning with  paragraph  287  under  the  heading  "Analysis  of  Liquid 
Fuels." 


FUEL  OIL  TESTS  AND  THEIR  TABULATION  333 

TABULATION  OF  FUEL  OIL  TEST  DATA 
TABLE  1.     Data  and  Results  of  Evaporative  Test 
Adapted  from  Code  of  1915 

(I)1         Test  of boiler  located  at 

to  determine conducted  by 

(2)  Number  and  kind  of  boilers 

(3)  Kind  of  furnace 

(a)  Type  of  burner 

(6)  Make  of  burner 

(c)  Number  of  burners 

(4)  Furnace  dimensions width length height 

(a)  Approximate  area  of  air  openings  in  furnace  floor sq.  in. 

(6)  Approximate  area  of  air  openings  around  burners sq.  in. 

(c)  Total  area  of  air  openings sq.  in. 

(d)  Total  area  of  air  openings  per  rated  horsepower sq.  in. 

(e)  Volume  of  furnace cu.  ft. 

(/)  Distance  from  furnace  floor  to  nearest  heating  surface ft. 

(5)  Water  heating  surface sq.  ft. 

(6)  Superheating  surface sq.  ft. 

(7)  Total  heating  surface sq.  ft. 

Date,  Duration,  Etc. 

(8)  Date 

(9)  Duration hr. 

(10)  Kind  of  fuel  oil 

(a)  Gravity  of  fuel  oil  at  60  deg.  (specific  gravity) 

(6)  Gravity  of  fuel  oil  at  60  deg.  (Baume  scale) 

(c)  Flash  point  of  oil deg. 

(d)  Viscosity  of  oil  at deg deg.    Engler. 

(e)  Method  of  atomizing  oil 

Average  Pressures,  Temperatures,  Etc. 

(11)  Steam  pressure  by  gage  in  boiler Ib.  per  sq.  in. 

(a)  Steam  pressure  at  superheater  outlet Ib.  per  sq.  in. 

(6)  Steam  pressure  at  oil  burners Ib.  per  sq.  in. 

(c)  Oil  pressure  at  burner Ib.  per  sq.  in. 

(d)  Barometric  pressure in.  of  mercury. 

(12)  Temperature  of  steam  at  superheater  outlet deg. 

(a)  Normal  temperature  of  saturated  steam deg. 

(6)  Temperature  of  steam  at  oil  burner deg. 

(c)  Temperature  of  oil  at  burner deg. 

(13)  Temperature  of  feed  water  entering  boiler deg. 

(a)  Temperature  of  feed  water  entering  economizer deg. 

(6)  Increase  of  temperature  of  water  due  to  economizer deg. 

(14)  Temperature  of  gases  leaving  boilers deg. 

(a)  Temperature  of  gases  leaving  economizer deg. 

(6)  Decrease  of  temperature  of  gases  due  to  economizer deg. 

(c)  Temperature  of  furnace deg. 

1  These  numbers  correspond  in  so  far  as  possible  with  numbers  given  in 
the  A.S.M.E.  Code  of  1915. 


334  FUEL  OIL  AND  STEAM  ENGINEERING 

(15)  Draft  between  damper  and  boiler in.  of  water 

(a)  Draft  in  main  flue  near  boilers in. 

(6)  Draft  in  main  flue  between  economizer  and  chimney in. 

(c)  Draft  in  furnaces in. 

(d)  Draft  in  ash  pits in. 

(16)  State  of  weather 

(a)  Temperature  of  .external  air deg. 

(6)  Temperature  of  air  entering  ash  pit deg. 

(c)  Relative  humidity  of  air  entering  ash  pit per  cent. 

Quality  of  Steam 

(17)  Percentage  of  moisture  in  steam  or  number  of  degrees 

of  superheating per  cent,  or  deg. 

(18)  Factor  of  correction  for  quality  of  steam " 

Total  Quantities 

(19)  Weight  of  fuel  oil  as  fired1 

(20)  Percentage  of  water  in  fuel  oil  as  fired.  .  . per     cent. 

(21)  Total  weight  of  water  free  fuel  oil  consumed Ib. 

(25)  Total  weight  of  water  fed  to  boiler Ib. 

(26)  Total  water  evaporated  corrected  for  quality  of  steam Ib. 

(a)  Total  weight  of  steam  fed  to  burner Ib. 

(6)  Steam  fed  to  burner  in  per  cent,  of  total  water  evaporated  per  cent. 

(27)  Factor  of  evaporation,  based  on  temperature  of  water  entering 

boilers 

(28)  Total  equivalent  evaporation  from  and  at  212  deg.1 Ib, 

Hourly  Quantities  and  Rates 

(29)  Oil  free  from  water  consumed  per  hour Ib. 

(30)  Oil  free  from  water  per  hour  per  burner Ib. 

(a)  Oil  free  from  water  per  cu.  ft.  of  furnace  volume  per  hour.  .  .  .Ib. 

(31)  Water  evaporated  per  hour,  corrected  for  quality  of  steam Ib. 

(a)  Steam  fed  to  burners  per  hour Ib. 

(6)  Equivalent  evaporation  from  and  at  212  deg.  of  steam  fed  to 

burner  per  hour Ib. 

(32)  Equivalent  evaporation  per  hour  from  and  at  212  deg.2 Ib. 

(33)  Equivalent  evaporation  per  hour  from  and  at  212  deg.  per 

sq.  ft.  of  water  heating  surface Ib. 

Capacity 

(34)  Equivalent  evaporation  per  hour  from  and  at  212  deg. 

(same  as  line  32) Ib. 

(a)  Boiler  horsepower  developed   (line  32  -h  34^) Bl.   H.P. 

(35)  Rated  capacity  per  hour,  from  and  at  212  deg Ib. 

(a)  Rated    boiler    horsepower Bl.    H.P. 

(36)  Percentage   of  rated   capacity   developed per  cent. 

Economy 

(37)  Wated  fed  per  Ib.  of  fuel  oil  as  fired  (item  25  +  item  19) Ib. 

(38)  Water  evaporated  per  Ib.  of  water  free  fuel  oil  (item  26  -J-item  21)  Ib. 

1  The  term  "as  fired"  means  actual  conditions,  including  moisture. 

2  The  symbol  U.  E.,  meaning  Units  of  Evaporation,  may  be  substituted 
for  the  expression  "Equivalent  Evaporation  from  and  at  212  deg." 


FUEL  OIL  TESTS  AND  THEIR  TABULATION  335 

(39)  Equivalent  evaporation  from  and  at  212  deg.  per  Ib.  of  fuel  oil 

as  fired  (item  28  -r-  item  19) Ib. 

(40)  Equivalent  evaporation  from  and  at  212  deg.  per  Ib.  of  water 

free  fuel  oil  (item  28  -7-  item  21) Ib. 

(a)  Equivalent  evaporation  from  and  at  212  deg.  of  steam  fed 

to  burner  per  Ib.  of  fuel  oil  free  from  water  (item  26a  X 

item  27  -s-item  21) Ib. 

(6)  Net  equivalent  evaporation  from  and  at  212  deg.  per  Ib.  of  oil 

free  from  water  (item  40  —item  40a) Ib. 

Calorific  Value 

(42)         Calorific  value  of  1  Ib.  of  fuel  oil  as  received  by  calorimeter ....  B.t.u. 
(a)    Calorific  value  of  1  Ib.  of  water  free  fuel  oil B.t.u. 

Efficiency 

(44;         Efficiency  of  boiler  and  furnace. 

IAA  ^  Item  40  X  970-4 

100  X  per  cent. 

Item  42a 

(a.  Net  efficiency  of  boiler  and  furnace. 

i™  vx  Item  406  X  970.4 

100  X =-r-    -ns —    — per  cent. 

Item  42a 

Cost  of  Evaporation 

(46)  Cost  of  fuel  oil  per  bbl.  of  42  gals,  delivered  in  boiler  room . .  .dollars. 

(47)  Cost  of  fuel  oil  required  for  evaporating  1000  Ib.  of  water 

under  observed  conditions dollars. 

(48)  Cost  of  fuel  oil  required  for  evaporating  1000  Ib.  of  water 

from  and  at  212  deg dollars. 

Smoke  Data 

(49)  Percentage  of  smoke  as  observed per  cent. 

(a)  Weight  of  soot  per  hour  obtained  from  smoke  meter 

(51)         Analysis  of  Dry  Gases  by  Volume. 

(a)  Carbon  dioxide  (CO2) per  cent. 

(6)  Oxygen  (O) per  cent. 

(c)  Carbon  monoxide  (CO) per  cent. 

(d)  Hydrogen  and  hydrocarbons per  cent. 

(e)  Nitrogen  by  difference  (N) per  cent. 

(53)         Ultimate  analysis  of  fuel  oil. 

(a)  Carbon  (C) per  cent. 

(6)  Hydrogen  (H) per  cent. 

(c)  Oxygen  (O) per  cent. 

(d)  Nitrogen  (N) per  cent. 

(e)  Sulphur  (S) per  cent. 

(/)  Ash per  cent. 

100  per  cent. 

(gr)  Water  in  sample  of  fuel  oil  as  received per  cent. 

(55)         Heat  balance,  based  on  fuel  oil  free  from  water; 


336 


FUEL  OIL  AND  STEAM  ENGINEERING 


B.t.u.      Per  cent. 


(a)  a.  Total  heat  absorbed  by  boiler  ......... 

6.  Heat  absorbed  for  atomization  ......... 

c.  Net  heat  absorbed  for  power  ........... 

(6)  Loss  due  to  water  in  fuel  oil  .............. 

(c)  Loss  due  to  water  from  burning  H  .......... 

(d)  Loss    due    to    heat    carried    away    by    dry 

gases  .................................          For  numerical 

(e)  Loss  due  to  carbon  monoxide  .............          example  com- 

(/)  a.  Loss    due    to    generation   of    steam   for         pletely  solved, 

atomization  ...........................         see  page  327. 

b.  Loss  due  to  superheat  of  steam  used  for 

atomization  ......................... 

c.  Total  loss  due  to  atomization  ........... 

(0)  Loss  due  to  moisture  in  entering  air  ........ 

(h)  Stray  losses  ...........................  .  . 

(1)  Total  calorific  value  of  1  Ib.  of  fuel  oil  free 

from  water  (item  42a)  100 

TABLE  2.  —  Principal  Data  and  Results  of  Boiler  Test 

(1)  Oil  Burners.  —  No  ............  Type  ..........  Make  .  .  .  ............ 

(2)  Total  heating   surface  ....................................  sq.   ft. 

(3)  Date  ......................................  .................... 

(4)  Duration  ...................................................  hr. 

(5)  Kind  and  gravity  of  fuel  oil  ...................................... 

(6)  Steam  pressure  by  gage  ......  .  .....................  Ib.  per  sq.  in. 

(a)  Oil  pressure  at  burner  ........................  Ib.  per  sq.  in. 

(7)  Temperature  of  feed  water  entering  boiler  .....................  deg. 

(a)   Temperature  of  oil  at  burner  .........................  deg. 

(8)  Percentage  of  moisture  in  steam  or  number  of  degrees  of  super- 

heating ......................................  per  cent,  or  deg. 

(9)  Percentage  of  water  in  oil  .............................  per  cent. 

(10)  Oil  free  from  water  per  hour  ..................................  Ib. 

(11)  Oil  free  from  water  per  hour  per  burner  ........................  Ib. 

(12)  Equivalent  evaporation  per  hour  from  and  at  212  deg  ............  Ib. 

(13)  Equivalent  evaporation  per  hour  from  and  at  212  deg.  per  sq. 

ft.  of  heating  surface  ........................................  Ib. 

(14)  Rated  capacity  per  hour,  from  and  at  212  deg  ...................  Ib. 

(15)  Percentage   of   rated    capacity   developed  ................  per   cent. 

(16)  Equivalent  evaporation  from  and  at  212  deg.  per  Ib.  oil  free  from 

water  ............................  .......................  Ib. 

(a)  Per  cent,  of  total  steam  used  by  burner  ............  per   cent. 

(17)  Net  equivalent  evaportion  from  and  at  212  deg.  per  Ib.  of  oil  free 

from  water  (deducting  steam  used   by  burner)  ...............  Ib. 

(18)  Calorific  value  of  1  Ib.  of  oil  as  received,  by  calorimeter  .........  B.t.u 

(19)  Calorific  value  of  1  Ib.  of  oil  free  from  water  ................  B.t.u. 

(20)  Efficiency  of  boiler  and  furnace  .........................  per  cent. 

(21)  Net  efficiency  (deducting  steam  used  by  burners)  .........  per  cent. 


CHAPTER  XL 

THE    USE    OF    EVAPORATIVE    TESTS    IN    INCREASING 
EFFICIENCY  OF  OIL  FIRED  BOILERS 

To  the  operating  engineer  it  may  seem  that  the  somewhat 
elaborate  rules  for  conducting  evaporative  tests  of  steam  boilers 
are  of  little  interest.  It  is  his  province  to  run  the  boilers  as 
economically  as  he  can,  to  keep  them  clean  and  in  proper  repair, 
and  above  all  to  keep  the  plant  in  continuous  operation.  There 
is  one  very  important  function  of  boiler  tests,  however,  which 
makes  them  invaluable  to  the  broad-gage  operating  engineer  who 
is  desirous  of  securing  the  best  possible  results  from  his  plant. 
This  is  the  use  of  the  evaporative  test  as  a  guide  in  determining 
what  is  the  best  furnace  arrangement,  the  best  style  of  oil 
burner,  and  the  best  draft  conditions  for  the  particular  boilers 
he  is  operating.  Thus  by  making  a  careful  test  under  certain 
conditions  and  then  making  another  test,  or  sometimes  a  series 
of  tests,  under  different  conditions,  it  is  possible  to  determine 
from  the  relative  efficiencies  obtained  just  how  the  boiler  should 
be  operated.  It  will  not  be  out  of  place,  therefore,  to  discuss 
briefly  the  various  changes  that  may  be  made  in  the  boiler 
operation,  which  when  intelligently  carried  out  will  lead  to 
higher  efficiencies. 

Furnace  Arrangement. — Perhaps  the  most  important  part 
of  an  oil  fired  boiler  is  its  furnace  arrangement.  In  a  previous 
chapter  a  number  of  different  furnaces  were  described,  but  it  was 
not  stated  which  was  the  most  efficient.  This  must  be  deter- 
mined by  testing  the  boiler  under  actual  operating  conditions, 
first  with  one  furnace  arrangement,  then  with  another,  being 
guided  in  making  changes  by  the  results  obtained  in  the  different 
tests.  It  is  impossible  to  design  a  furnace  that  will  be  right  for 
all  conditions,  as  with  different  grades  of  fuel  oil  or  different 
makes  of  boiler  or  different  draft  conditions,  different  furnace 
arrangements  are  required.  Fortunately  it  is  possible  to  make 
minor  changes  in  the  furnace  very  easily,  as  these  involve  usually 
only  an  alteration  of  the  location  of  fire  brick  on  the  furnace 
22  337 


338  FUEL  OIL  AND  STEAM  ENGINEERING 

floor.  It  is  thus  possible  to  increase  or  decrease  the  size  of  air 
openings,  or  to  change  them  in  such  a  way  as  to  allow  more  air 
to  enter  at  one  part  of  the  furnace,  such  as  directly  under  the 
flame,  and  less  at  another  part  where  it  is  not  needed.  It  is  also 
possible,  without  much  difficulty,  to  alter  a  furnace  that  has 
been  designed  for  a  front  shot  burner  and  make  it  suitable  for  a 
back  shot  burner,  and  thus  it  may  be  found  by  actual  tests  which 
of  these  two  types  of  furnace  is  best  suited  to  the  particular 
boiler. 

In  testing  the  different  arrangements  it  is  very  important  to 
test  the  boiler  for  capacity  as  well  as  economy,  as  it  may  some- 


FIG.   199. — The  furnace  interior. 

Here  is  shown  the  furnace  interior  of  an  oil  fired  boiler  similar  in  design  to  the  specifi- 
cations given  in  this  chapter.  Note  the  V-shaped  arrangement  in  the  brickwork  in  order 
to  admit  air  for  the  economic  burning  of  the  fuel  oil. 

times  happen  that  the  furnace  that  is  most  efficient  at  ordinary 
loads  is  not  capable  of  forcing  the  boiler  enough  to  carry  the 
heavy  loads  sometimes  required.  In  such  a  case  it  may  be  neces- 
sary to  adopt  a  less  efficient  furnace,  as  it  is  usually  of  supreme 
importance  for  the  boiler  to  be  capable  of  carrying  an  overload 
when  required. 

Oil  Burners. — Boiler  tests  are  of  great  value  in  determining 
what  make  and  style  of  oil  burner  is  the  best  to  use  under  the 
given  conditions.  In  testing  oil  burners  it  is  of  extreme  impor- 
tance to  measure  the  steam  used  by  the  burner  and  determine  the 
net  efficiency  of  the  boiler;  for  one  kind  of  burner  may  produce 


INCREASING  EFFICIENCY  OF  OIL  FIRED  BOILERS    339 

better  furnace  efficiency  than  another,  and  yet  use  so  much  steam 
for  atomizing  as  to  make  it  an  uneconomical  burner  to  use.  After 
deciding  on  the  type  of  burner  to  use,  tests  should  be  made  with 
varying  quantities  of  atomizing  steam  with  the  same  burner,  the 
object  being  not  to  find  out  the  least  quantity  of  steam  that  may 
be  used  for  atomizing  but  to  determine  the  quantity  of  steam 
that  secures  the  best  net  efficiency  of  the  boiler. 

The  temperature  and  pressure  of  the  oil  are  intimately  con- 
nected with  the  quantity  of  atomizing  steam  required.  In  the 
case  of  mechanical  atomization,  such  as  is  used  in  marine  work, 
high  pressure  and  high  temperatures  are  used  and  no  steam  is 
required.  In  general  it  may  be  said  that  the  hotter  the  oil  and 
the  higher  its  pressure,  the  less  atomizing  steam  is  needed.  Dif- 
ferent oils  require  different  temperatures,  and  the  temperature 
should  always  be  kept  well  below  the  flash  point  of  the  oil.  By 
testing  the  boiler  with  the  oil  first  at  one  temperature  and  then  at 
another,  and  varying  the  quantity  of  steam  to  suit,  much  infor- 
mation can  be  obtained  as  to  the  most  economical  method  of 
operation. 

Apart  from  the  quantity  of  steam  used,  other  changes  that 
may  be  made  in  the  burner  consist  in  varying  the  size  of  the  steam 
and  oil  slots,  altering  the  height  of  the  burner  in  reference  to  the 
furnace  floor,  and  changing  the  angle  of  the  flame  in  reference  to 
the  grates. 

Draft. — The  quantity  of  air  entering  the  furnace  depends  on 
the  intensity  of  the  draft,  and  the  area  of  openings  for  the  admis- 
sion of  air  to  the  furnace.  The  quantity  of  air  may  be  reduced 
by  partially  closing  the  boiler  damper  or  the  ash  pit  doors,  or  it 
may  be  increased  by  enlarging  the  openings  in  the  furnace  floor. 
Thus  it  is  possible  to  operate  with  large  openings  and  light  draft, 
or  .with  small  openings  and  strong  draft.  A  careful  test  of  the 
boiler  will  determine  at  once  which  of  these  conditions  gives  the 
best  results.  If  the  load  on  the  plant  is  variable  it  is  necessary  to 
have  the  air  openings  large  enough  to  admit  sufficient  air' for  the 
maximum  load  at  full  draft.  Then  for  lighter  loads  the  damper 
or  ash  pit  doors  must  be  operated.  When  making  tests  the  read- 
ings of  the  draft  gage  at  various  points  in  the  setting  should  be 
carefully  observed,  and  loss  of  draft  due  to  the  gases  passing 
through  the  setting  noted.  Thus,  if  the  draft  in  the  fur- 
nace is  0.2  in  and  the  draft  in  front  of  the  damper  is 0.3  in.,  there  is 
loss  of  0.1  in.  between  the  damper  and  the  furnace.  This  loss  of 


340  FUEL  OIL  AND  STEAM  ENGINEERING 

draft  varies  with  the  volume  of  gases  just  as  the  drop  in  pressure 
due  to  steam  flowing  through  an  orifice  varies  with  the  quantity 
of  steam  flowing.  If  the  quantity  of  excess  air  increases,  there- 
fore, the  loss  of  draft  also  increases.  By  connecting  a  draft  gage 
so  as  to  measure  the  difference  in  the  draft  at  the  two  points,  it 
will  serve  as  an  approximate  indicator  of  the  amount  of  excess  air. 

Flue  Gas  Analysis  for  Maximum  Efficiency. — The  analysis  of 
the  flue  gases  serves  as  an  accurate  means  of  determining  how  to 
set  the  dampers,  and  is  the  most  valuable  guide  in  securing  the 
best  efficiency,  both  during  an  evaporative  test  and  in  regular 
operation.  In  general,  it  may  be  said  that  the  best  efficiency  is 
obtained  when  the  greatest  percentage  of  carbon  dioxide  (CO2) 
occurs,  without  the  presence  of  carbon  monoxide  (CO).  If  CO 
begins  to  appear  in  the  gas  analysis  it  is  useless  to  increase  the 
CO2  further,  as  any  gain  due  to  reducing  the  excess  air  is  more 
than  offset  by  the  loss  due  to  incomplete  combustion.  The  pres- 
ence of  CO  is  always  more  harmful  than  is  indicated  by  the  calcu- 
lated loss  for  unconsumed  carbon,  for  if  carbon  is  only  partially 
consumed  it  is  certain  that  some  of  the  hydrogen  is  also  passing 
off  unconsumed  in  the  form  of  hydrocarbons,  thus  causing  a  far 
greater  loss.  This  loss  due  to  unconsumed  hydrogen  does  not 
appear  in  the  ordinary  gas  analysis,  and  it  is  in  connection  with 
this  item  that  the  heat  balance  is  of  special  value.  Item  (h)  of 
the  heat  balance,  which  is  found  by  subtracting  the  heat  ac- 
counted for  from  the  heat  supplied,  includes  the  loss  due  to  un- 
consumed hydrogen,  and  if  accurate  tests  are  made  it  will  be 
found  that  this  item  is  always  greater  the  more  CO  is  found  in 
the  gases. 

If  the  furnace  is  properly  designed  it  should  be  possible  to 
secure  13^  per  cent,  to  14  per  cent.  C02,  with  not  over  3  per  cent, 
oxygen,  and  without  a  trace  of  CO,  using  not  over  15  per  cent, 
or  20  per  cent,  excess  air.  These  results  must  be  secured  to  give 
the  best  economical  results,  and  if  they  cannot  be  secured  by 
changing  the  draft  or  the  burners,  it  will  then  follow  that  there 
is  something  wrong  with  the  furnace  arrangement. 

It  will  be  found  that  there  is  a  very  intimate  relation  between 
the  furnace,  the  burner,  and  the  draft.  Thus  the  intensity  of 
draft  and  amount  of  atomizing  steam  that  give  best  results  with 
one  furnace,  may  give  poor  results  with  another;  yet  by  read- 
justing the  dampers  and  burner  valves  to  suit  the  new  conditions, 
better  results  than  ever  may  be  obtained.  With  too  much  steam 


INCREASING  EFFICIENCY  OF  OIL  FIRED  BOILERS    341 


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342 


FUEL  OIL  AND  STEAM  ENGINEERING 


the  flame  may  be  carried  too  far  beyond  the  air  openings,  causing 
a  poor  mixture  of  air  and  gases.  This  would  result  in  a  poor 
gas  analysis,  although  the  total  quantity  of  air  may  be  correct. 

There  are  so  many  variations  that  can  be  made,  that  it  is 
usually  impractical  to  make  a  complete  evaporative  test  for 

BOILER  OPERATION   REPORT 
PACIFIC  GAS  AND  ELECTRIC  COMPANY        OPERATION  AND  MAINTENANCE  DEPT 

OBSERVATIONS  ON  BOILER  No IN  STATION  

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FIG.  201. — Typical  form  for  boiler  operation  report. 

Here  is  how  the  Pacific  Gas  and  Electric  Company,  a  corporation  operating  the  largest 
system  of  oil-fired  steam  power  plants  in  the  world,  keeps  its  records  on  evaporative  tests 
for  bettering  power  plant  economy. 

each  set  of  conditions.  It  is  possible,  however,  to  obtain  com- 
parative data  in  a  single  test,  by  varying  the  conditions  at  the 
end  of  each  hour,  or  each  two  hours.  By  carefully  observing 
the  quantity  of  oil  and  water  used  each  hour,  a  fairly  accurate 


INCREASING  EFFICIENCY  OF  OIL  FIRED  BOILERS    343 

comparison  of  efficiencies  under  different  conditions  may  be 
obtained.  This,  combined  with  the  flue  gas  analysis,  makes  a 
valuable  guide  for  efficient  operation. 

Regulation. — When  an  oil  fired  boiler  is  in  operation  there  are 
three  variables  under  control  of  the  fireman,  viz. : 

The  quantity  of  oil  burned. 

The  quantity  of  atomizing  steam  used,  and 

The  quantity  of  air  supplied. 


FIG.  202. — Venturi  meter  for  measuring  water  supply  at  the  Long  Beach 
Plant  of  the  Southern  California  Edison  Company  shown  installed  on  piping 
in  upper  right  center. 

The  quantity  of  oil  burned  is  determined  by  the  amount  of 
steam  required  in  the  plant,  and  must  be  varied  accordingly. 
When  there  are  several  boilers  in  battery  the  amount  burned 
under  each  boiler  may  be  varied  by  operating  the  oil  valves  at 
the  burners,  or  the  total  amount  in  the  plant  may  be  changed  by 
altering  the  oil  pressure  at  the  oil  pump.  Whenever  the  quan- 
tity of  oil  burned  is  varied,  there  should  be  a  corresponding  varia- 
tion in  the  quantity  of  atomizing  steam  and  the  quantity  of  air. 


344  FUEL  OIL  AND  STEAM  ENGINEERING 

There  are  now  on  the  market  devices  which  regulate  all  three 
variables  automatically  according  to  the  load  on  the  plant.  Il- 
lustrations of  automatic  firing  systems  are  shown  on  pages  331 
and  341.  The  essential  requisites  for  a  device  of  this  kind  are 
that  it  shall  be  reliable  in  operation,  and  that  when  it  has  once 
been  set  to  give  proper  CO2  readings  at  certain  loads,  it  will 
always  come  back  to  the  same  position  for  the  same  load.  While 
it  is  possible  under  test  conditions  to  secure  just  as  high  efficiency 
with  hand  regulation  as  with  the  automatic,  it  will  usually  be 
found  that  the  automatic  regulator  produces  better  every-day 
economy  under  operating  conditions. 

Records. — Complete  evaporative  tests  cannot  be  made  every 
day  in  an  ordinary  plant,  but  it  is  possible  to  take  sufficient  ob- 
servations to  secure  a  daily  record  of  the  important  items  enter- 
ing into  the  operation  of  a  boiler.  A  form  that  is  convenient 
for  such  a  record  is  illustrated  in  Fig.  201.  By  carefully  study- 
ing these  records,  together  with  the  results  of  evaporative  tests, 
it  is  possible  to  maintain  the  operation  of  a  boiler  plant  at  a 
very  efficient  point. 

By  operation  at  the  most  efficient  point  we  save  and  it  is  well 
to  remember  in  these  days  of  national  crisis,  that  "to  save  is  to 
serve." 

PRACTICAL  ILLUSTRATIONS  OF  ECONOMY  STUDY 

As  an  illustration  of  what  can  be  accomplished  in  actual  prac- 
tice by  the  use  of  boiler  tests,  combined  with  intelligent  changes  of 
furnace  arrangement  and  operating  details,  the  following  de- 
scription of  work  performed  in  one  of  the  large  oil  burning  plants 
in  San  Francisco  will  be  of  interest : 

In  order  to  increase  the  efficiency  and  capacity  of  the  boilers, 
certain  changes  were  made  on  the  boiler  shown  in  Fig.  203.  To 
determine  what  improvements  had  been  effected  a  series  of 
tests  was  run  before  and  after  the  changes  were  made.  The 
amount  of  oil  burned  in  the  furnace  was  measured  by  a  meter  and 
the  amounts  of  steam  generated  and  steam  used  by  the  burners 
were  measured  by  General  Electric  flow  meters. 

General  Furnace  Arrangement. — Before  making  the  changes, 
the  furnace  in  the  boiler  was  arranged  as  shown  in  Fig.  86  and  the 
baffles  between  the  gas  passages  were  located  as  shown  in  Fig.  203. 
Most  of  the  baffle  bricks  in  front  of  the  flame  plates  between  the 
1st  and  2nd  passes  were  missing,  thus  allowing  a  large  percentage 


INCREASING  EFFICIENCY  OF  OIL  FIRED  BOILERS    345 


CoHcKere 
BULGED    UP    AHD    Core/reo    To 
DEPTH   OF    6*    wtTH    Sot>T, 

FIG.  203. — Arrangement   of   baffles   between   gas   passages  before   making    the 
changes  for  the  test. 


FIG.  204. — Arrangement   of   baffles   between   gas   passages   after   making    the 
changes  for  the  test. 


346 


FUEL  OIL  AND  STEAM  ENGINEERING 


of  the  gases  from  the  furnace  to  pass  directly  into  the  2nd  pass, 
the  flame  plates  themselves  having  been  burned  away  in  a  num- 
ber of  places.  The  space  between  the  bottom  of  the  rear  baffle 


FIG.  205. — Checkerwork  and  housings  installed  around  burners. 

and  the  bridge  wall  was  also  very  small  as  shown  on  the  sketch. 
This  was  remedied  by  moving  back  the  bottom  of  the  baffle  to  a 
position  as  shown  in  Fig.  204.  All  of  the  flame  plates  which  were 


FIG.  206. — Sketch  of  grate  bars  used  during  test. 

in  bad  shape  were  renewed  and  new  bricks  put  in  front  of  them, 
thus  making  the  new  baffles  as  tight  as  possible. 

The  furnace  arrangement  as  shown  in  Fig.  86  was  changed  to 
conform  to  the  arrangement  as  shown  in  Fig.  87.     New  grate  bars 


INCREASING  EFFICIENCY  OF  OIL  FIRED  BOILERS    347 


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348  FUEL  OIL  AND  STEAM  ENGINEERING 

having  wide  air  spaces  were  also  installed,  a  2  ft.  6  in.  bar  being 
used  next  to  the  bridge  wall  and  a  3  ft.  6  in.  long  bar  next  to  this. 
These  bars  which  are  shown  in  Fig.  206  have  a  net  free  area  of  about 
65  per  cent.  The  checkerwork  and  housings  installed  around  the 
burners  are  shown  in  Fig.  205. 

New  piping  was  installed  for  the  steam  and  oil  to  the  burners. 
The  general  view  of  the  piping  and  other  details  of  the  boiler 
front  is  shown  in  Fig.  60.  Two  flanges,  inserted  for  bringing  about 
an  arrangement  for  limiting  the  steam  to  burners,  had  a  steel 
disc  inserted  between  them,  this  disc  having  a  Jf  g  m-  h°le  drilled 
through  it.  When  the  boiler  is  running  at  rating  all  the  steam 
for  atomizing  passes  through  this  hole,  the  valve  on  the  by- 
pass around  the  disc  being  closed.  When  it  is  desired  to  carry 
a  heavy  load  on  the  boiler  the  lower  or  by-pass  valve  is  opened 
and  enough  steam  can  be  obtained  for  any  overload  desired.  The 
valves  having  rising  stems,  one  can  tell  at  a  glance  whether  the 
by-pass  valve  is  opened  or  closed. 

The  damper  control  was  brought  to  the  front  of  the  boiler  and 
arranged  so  that  the  damper  could  be  opened  or  closed  in  very 
small  increments.  It  was  found  that  the  damper  did  not  fit 
tight  all  around  as  proved  by  the  draft  readings  taken  in  the 
boiler  with  the  damper  and  ash  pit  doors  closed  as  tight  as  pos- 
sible. This  defect  was  not  completely  remedied  as  there  was 
still  some  leakage  at  this  point  during  the  tests. 

The  location  of  the  peep  hole  in  the  south  wall  was  changed  so 
that  a  view  of  the  front  walls  and  tubes  for  some  distance  back 
from  it  could  be  obtained.  This  enabled  the  operator  to  see  the 
end  of  the  flame  at  all  times  and  to  determine  when  the  fires 
were  smoking.  Peep  holes  were  also  put  in  the  side  walls  close 
to  the  burners  so  that  the  flame  and  furnace  could  be  observed 
at  these  points. 

By  building  a  small  wall  in  front  of  .the  mud  drum  and  laying 
a  plate  from  the  top  of  this  wall  to  the  mud  drum,  the  possi- 
bility of  gases  getting  under  the  drum  and  by-passing  the  3d 
pass  was  eliminated.  A  plate  14  in.  wide  was  laid  on  top  of  the 
upper  tubes  and  against  the  back  headers,  the  effect  of  this  being 
to  force  the  gases  to  pass  over  the  entire  tube  surface  in  the  rear 
pass. 

Table  Showing  Economy  Data. — The  following  table  shows  the 
operating  conditions  and  loads  which  could  be  carried  on  this 
boiler  before  and  after  the  changes  were  made  and  the  boiler 


INCREASING  EFFICIENCY  OF  OIL  FIRED  BOILERS     349 


cleaned.  This  table  shows  the  average  of  the  15  minute  readings 
during  the  periods  for  which  the  tests  were  run.  In  all  cases 
the  conditions  remained  practically  constant  during  the  run. 

The  first  five  columns  of  the  table  show  the  tests  made  on 
April  19,  20  and  21  before  any  changes  had  been  made  on  the 
boiler,  except  that  before  the  trials  of  April  20  the  soot  was 
blown  from  the  tubes.  This  accounts  for  the  much  lower  flue 
gas  temperature  for  the  first  test  on  April  20  as  compared  with 
the  evening  test  of  April  19,  at  approximately  the  same  load. 
The  test  of  April  21  shows  the  maximum  load  which  could  be 
obtained  on  the  boiler  prior  to  the  changes. 

The  last  four  columns  in  the  table  show  the  results  obtained 
after  the  changes  had  been  made.  The  following  summary  shows 
a  comparison  of  the  two  maximum  loads  run : 

COMPARATIVE  ECONOMIC  RESULTS 


April  21,  May  14, 

before  changes    |  after  changes  had 
had  been  made  been  made 


Boiler  pressure 

Oil  pressure 

Oil  temperature 

Draft  in  breeching 

Draft  in  top  3d  pass  

Draft  in  bot.  3d  pass 

Draft  in  bot.  2d  pass 

Draft  in  top  2d  pass 

Draft  in  top  1st  pass 

Draft  in  furnace 

Draft  in  ash  pit 

Temp,  of  flue  gases ' . 

Load  on  boiler 

Per  cent,  of  rating  developed 

Gross  efficiency 

Steam  to  burners 

Net  efficiency 


196  Ibs. 

52  Ibs. 

177° 
0.225" 
0.21  " 
0.21  " 
0.155" 
0.039" 
0.016" 
0.083" 
0.078" 
610° 

755  h.p. 

144% 
69.5% 

4.28% 
66.5% 


199  Ibs. 

55  Ibs. 

180° 
0.315" 
0.271" 
0.243" 
0.171" 
0.066" 
0.042" 
0.096" 
0.103" 
642° 
972  h.p. 
186% 
76.4% 

3.37% 
73.82% 


Conclusions  from  Test  Data. — Thus  the  capacity  of  the  boiler 
was  increased  from  144  per  cent,  of  rating  to  186  per  cent,  of 
rating,  a  net  gain  of  29  per  cent,  in  the  amount  of  steam  generated. 
At  the  same  time  the  net  efficiency  was  increased  from  66.5  per 
cent,  to  73.8  per  cent.  This  increase  in  net  efficiency,  it  will  be 


350  FUEL  OIL  AND  STEAM  ENGINEERING 

noted  was  helped  out  by  the  saving  in  the  amount  of  steam  for 
atomizing,  the  latter  item  having  been  reduced  from  4.28  per 
cent,  of  the  total  steam  generated  to  3.37  per  cent.  These 
efficiencies  are  only  comparative  as  a  heat  balance  shows  that 
the  efficiency  is  probably  higher  in  each  case  than  that  given. 
The  discrepancy  is  due  probably  to  an  error  in  the  oil  meter. 

A  comparison  of  the  tests  at  other  ratings  shows  a  marked  im-' 
proVement  in  the  operation  of  the  boiler,  particularly  in  the 
amount  of  steam  for  atomizing  the  oil.  Subsequent  to  the  tests 
enumerated  it  has  been  found  that  rating  could  be  obtained  on 
the  boiler  if  the  steam  for  atomizing  was  supplied  through  only 
a  Y±  in.  hole  in  the  disc  previously  mentioned.  Under  this  con- 
dition the  steam  for  atomizing  was  reduced  to  slightly  above 
2  per  cent. 


CHAPTER  XLI 
ECONOMIES  OBTAINED  IN  OIL  BURNING  PRACTICE 

When  a  boiler  is  fired  with  oil  there  are  no  ashes  to  carry 
away  unburned  fuel,  there  are  no  banked  fires  to  cause  poor  effi- 
ciency at  light  loads,  and  as  it  is  possible  to  secure  perfect  com- 
bustion with  very  little  excess  air,  the  efficiency  of  an  oil  fired 
boiler  is  naturally  higher  than  that  of  a  coal  fired  boiler. 

In  Table  1,  on  page  357  are  given  the  results  of  actual  tests 
that  have  been  made  from  time  to  time  on  oil  fired  boilers  with 
steam  atomizing  burners  at  different  locations  and  under  various 
conditions.  In  Table  2,  on  page  358  are  given  the  results  of 
tests,  made  by  the  Babcock  and  Wilcox  Co.  with  mechanically 
atomized  oil  burners,  taken  from  a  paper  by  Darrah  Corbet 
published  in  the  August  1920  Journal  of  the  American  Institute 
of  Electrical  Engineers.  These  tests  give  the  best  results  that 
can  be  expected  from  oil  fired  boilers.  Actual  results  obtained 
in  regular  operation  are  not  usually  as  good  as  the  results 
obtained  from  tests,  but  they  can  be  made  as  good  if  the  same 
care  is  exercised  in  keeping  the  boilers  clean,  regulating  the  air 
supply  and  all  the  minor  details  that  help  in  securing  high 
efficiency. 

There  is  very  little  data  available  to  show  just  how  closely 
modern  power  plants  approximate  to  test  results  in  every  day 
operation,  as  there  are  few  plants  that  keep  records  complete 
enough  and  accurate  enough  to  determine  the  daily  boiler  effi- 
ciency separate  from  the  complete  plant  efficiency.  The  usual 
method  of  recording  the  daily  efficiency  of  an  oil  burning  central 
station  is  by  the  ratio  of  kilowatt-hours  generated  to  barrels 
of  oil  burned.  While  this  is  an  excellent  method  of  determining 
the  overall  efficiency  of  the  plant  as  a  whole,  it  is  a  poor  method  of 
comparing  an  oil  burning  plant  with  a  coal  burning  plant  or  of 
comparing  one  oil  burning  plant  with  another.  There  are  so 
many  factors  that  enter  into  the  overall  efficiency,  such  as  pres- 
sure of  steam,  degree  of  superheat,  amount  of  vacuum,  economy 
of  prime  movers,  character  of  auxiliaries,  and  station  load 
factor,  that  the  mere  statement  of  kilowatt-hours  generated 

351 


352 


FUEL  OIL  AND  STEAM  ENGINEERING 


FIG.  208. — Boiler  front  at  Arizona  Power  Plant,  Phoenix,  Arizona.  A  world's 
record  was  here  established,  wherein  333.3  kilowatt  hours  of  electrical  energy 
were  generated  per  barrel  of  fuel  oil  burned. 


ECONOMIES  OBTAINED  IN  OIL  BURNING  PRACTICE    353 

per  barrel  of  oil  does  not  give  much  idea  of  what  efficiency  is  being 
obtained  from  the  oil  burning  boilers  unless  a  complete  detailed 
description  of  the  plant  is  included. 

It  is  probable  that  the  general  average  of  present  day  oil 
burning  central  stations  generate  from  200  to  240  kilowatt  hours 
per  barrel  of  oil,  when  operated  at  a  fair  load  factor.  This  is 
equivalent  to  from  25,000  to  30,000  B.t.u.  per  kilowatt  hour. 


60,000 


60,000 


B  40,000 


^sn.ooo 
pq 


20,000 


10,000 


1  1 

1 

l\\  1    Bal 

eJ 

on: 

0 

Temperature  -60  F. 
1  Bbl.-42  U.S.  Gals-  5.6140  cu.ft. 
Sp.Gr..-  140  ;  (130  +  deR.Baume') 
Heat  Value  of  Oil  -  1S500  B.T.U.  per  11 

ry  185  B.T.U.  variation  in  Heat  Value 
r  below  18500  per  Ib,  aid  to  or  subtract 
n  the  curve  values  for  B.T.U.  per 

TT 

I    ] 

ror  eve 
bove  o 
£  *ro 
Cw  Hr 

1 

1 

\\\ 

1 

1 

\ 

\v 

-12  Baum 

| 

"20 

0    .. 

s 

\ 

\\\ 

s 

\ 

\\\ 

s 

sS 

^ 

y,^ 

^ 

- 

V 

^ 

V< 

^ 

^ 

^ 

S. 

^ 

^ 

^ 

^ 

^ 

-^ 

^ 

*""• 

4CO 


100  2CO  300 

K.W.Hrs.per  Barrel  of  Oil 

FIG.  209.  —  Curve  showing  relation  between  K.W.H.  per  barrel  of  oil  and  B.T.U. 
per  K.W.H.  for  different  grades  of  oil. 

At  very  light  loads,  such  as  occur  in  standby  service,  the  effi- 
ciency may  drop  to  less  than  100  kilowatt  hours  per  barrel. 

While  records  giving  the  actual  efficiency  of  oil  fired  boilers 
under  regular  operating  conditions  are  rare,  a  very  close  ap- 
proximation of  the  performance  of  the  boilers  can  be  obtained 
from  the  flue  gas  analysis  and  the  temperature  of  the  escaping 
gases.  It  will  therefore  be  of  interest  to  note  some  of  the  actual 
Orsat  readings  taken  from  boilers  in  regular  service. 

23 


354 


FUEL  OIL  AND  STEAM  ENGINEERING 


The  following  readings  were  obtained  from  a  600  h.p.  Stirling 
Boiler  with  Peabody  Hammel  furnace.  No  special  adjustments 
were  made  and  the  object  of  taking  these  readings  was  to  obtain 
some  idea  of  the  performance  of  the  boiler  as  usually  fired : 


I*' 

-80^ 

Boiler  Efficiency 

iau 

too 

440 
420 
400 

380  ~ 

SCO'S 

340  | 
320  5 
300  * 

"•a 

2GO^ 

240  2 

220 
200 
180 
160 
140 
120 

/ 

^ 

A* 

.. 

/  j 

li\% 

\ 

,, 

f 

,£* 

• 

,, 

/ 

'/ 

/ 

f 

/ 

'/ 

V 

/ 

/  j 

'/ 

/ 

/ 

/ 

/  1 

/ 

/ 

/ 

/ 

/ 

/ 

/ 

/ 

/ 

/ 

S 

x 

s 

/ 

/ 

/ 

x 

X 

/ 

^ 
/ 

/ 

sS 

<S 

X 

x 

X 

^ 

X*" 

^ 

^ 

X 

X 

x 

+** 

.  —  ' 

^ 

^ 

^ 

,** 

^* 

*•*** 

^ 

^-x 

•* 

" 

27   26  25  24  23  22  21  20  13  18  17  16  15  14  13  12  11  10    9 
Pounds  Steam  per  K.W.  Hr.  (Gross) 


87654321 


FIG.  210. — Curve  showing  relation  between  steam  consumption  per  kw.  hour 
and  the  output  in  kw.  hours  per  barrel  of  oil  at  different  boiler  efficiencies. 


Average 


C02 

13.8 
14.2 
14.0 
12.0 

13.5 


3.0 
2.1 
2.2 
5.2 

3.1 


CO 

0.0 
0.1 
0.0 
0.0 

0.02 


Per  cent, 
excess  air 
calculated 

16.0 

12.5 

14.0 

32.0 


18.6 


The  following  readings  were  obtained  from  a  750  h.p.  Boiler 
of  the  water  leg  type,  with  vertical  baffles  and  burners  set  in  the 
front  wall: 


C02 
11.4 
12.2 
12.0 
12.3 


O 

5.4 
4.5 
4.8 
4.5 


CO 
0 
0 
0 
0 


Per  cent, 
excess  air 
39 
30 
32 
29 


Average 


11.9 


4.8 


32 


ECONOMIES  OBTAINED  IN  OIL  BURNING  PRACTICE    355 

At  this  point  an  effort  was  made  to  reduce  the  excess  air  by  par- 
tially closing  the  damper,  after  which  the  following  readings 
were  obtained: 

CO2  O  CO  Percent. 

excess  air 
13.6  2.8  0  17 

The  following  readings  were  obtained  from  a  773  h.p.  Parker 
boiler  with  horizontal  baffles  with  the  burners  set  in  the  front 
wall,  the  furnace  extending  the  full  length  of  the  boiler: 

CO2  O  CO  Per  cent. 

excess  air 

14.9  1.2  0.2  7 

15.4  0.5  0.9  4 

Since  these  readings  show  the  presence  of  carbon  monoxide  (CO), 
an  effort  was  made  to  obtain  perfect  combustion  by  opening 
the  damper  and  ashpit  doors  wide,  with  the  following  result: 

Per  cent. 
CO2  O  CO  excess  air 

15.2  0.6  0.5  5 

Since  CO  was  still  present  the  fires  were  cut  down,  slightly  reduc- 
ing the  capacity  of  the  boiler,  with  the  following  results: 

Per  cent. 
CO2  O  CO  excess  air 

14.3  2.4  0  12 

It  is  thus  seen  that  with  boilers  of  several  different  types,  and 
different  furnace  arrangements,  very  little  effort  on  the  part  of 
the  operators  is  required  to  obtain  air  regulation,  corresponding  to 
the  test  results  shown  in  the  table  of  tests  as  reproduced  in  this 
article. 

The  temperature  of  the  escaping  gases,  which  is  the  other 
important  item  affecting  the  efficiency  of  the  boilers  in  regular 
operation,  depends  on  five  things: 

1.  Regulation  of  air  supply 

2.  Cleanliness  of  the  boiler 

3.  Capacity  of  the  boiler 

4.  Design  of  the  boiler 

5.  Condition  of  the  boiler  brickwork  and  baffles 


356  FUEL  OIL  AND  STEAM  ENGINEERING 

Flue  gas  temperatures  in  actual  practice  run  all  the  way  from 
400°F.  for  clean  boilers  operating  at  their  rated  capacity  with  15 
or  20  per  cent,  of  excess  air,  up  to  800°F.  for  dirty  boilers  with 
leaky  baffles  operating  at  200  per  cent,  of  rating  with  50  to  100 
per  cent,  excess  air.  A  general  average  for  boilers  in  regular 
operation  is  about  550°F. 

The  following  results  were  obtained  on  a  524  h.p.  Babcock 
and  Wilcox  boiler  set  with  the  front  headers  9  feet  above  the 
floor,  equipped  with  a  Peabody  furnace.  The  setting  was  new, 
and  the  boiler  had  just  been  cleaned  inside  and  out.  The  boiler 
was  equipped  with  soot  blowers  which  were  operated  about  eight 
hours  before  the  observations  were  taken. 

Duration  of  test,  hrs 1.0  3.0 

Capacity — per  cent,  of  rating  (measured 

by  steam  flow  meter) 110.0  172.0 

Steam  pressure,  gage,  Ibs.  per  sq.  in 192 .0  198 . 0 

Degree  of  superheat,  deg.  F 75 . 0  73 . 0 

Draft  at  damper,  in.  water 0.01  0.23 

Carbon  dioxide  CO2% 14.4  14.3 

Temperature  escaping  gases,  deg.  F 431.5  457.5 

The  importance  of  keeping  a  boiler  clean  is  well  illustrated  by 
the  effect  on  the  flue  gas  temperature  of  blowing  the  soot  off  the 
tubes.  There  is  a  common  belief  that  when  burning  oil  there  is 
little  or  no  accumulation  of  soot.  This,  however,  is  not  the  case, 
for  while  the  quantity  of  soot  is  much  less  than  in  a  coal  fired 
boiler  it  is  still  an  ever  present  evil,  and  it  is  necessary  to  dust  the 
tubes  at  least  once  a  day  if  the  best  efficiency  is  to  be  obtained. 
The  following  readings  taken  in  regular  service,  on  an  823  h.p. 
Stirling  boiler  with  a  Peabody  Hammel  oil  furnace,  show  that 
blowing  the  soot  off  the  tubes  resulted  in  reducing  the  exit  tem- 
perature more  than  75°,  and  that  in  six  days  the  temperature 
gradually  built  up  to  more  than  it  had  been  before  the  tubes 
were  dusted. 

In  stand  by  plants,  where  it  is  necessary  to  operate  the  plant 
at  no  load  and  be  ready  to  pick  up  the  load  at  any  instant,  the 
boilers  must  be  kept  hot  even  though  no  steam  is  generated. 
With  coal  fired  boilers  this  is  accomplished  by  keeping  a  banked 
fire  on  the  grates.  With  oil  fired  boilers  the  fire  is  put  out 
completely,  and  when  the  steam  pressure  in  the  boiler  has  dropped 
as  low  as  permissible,  the  fire  is  relighted  and  the  steam  brought 
back  to  full  pressure.  During  the  time  the  fire  is  out  the  damper 


ECONOMIES  OBTAINED  IN  OIL  BURNING  PRACTICE     357 


a  s-i 


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Type  of  boiler 
Type  of  oil  burner 
Heating  surface,  sq 
Date 
Duration,  hours 


c  c 

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Specific  gravity 
Steam  pressure  ( 
Oil  pressure  at 
Temperature  of 


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358 


FUEL  OIL  AND  STEAM  ENGINEERING 


TABLE  2.* — RESULTS  OF  TESTS  ON  OIL-BURNING  BOILERS  WITH 
MECHANICAL  ATOMIZING  BURNERS 

OIL  BURNER  TEST— BABCOCK  &  WILCOX  BOILER 

BAYONNE,  NEW  JERSEY 

450  horsepower — 15.45  per  cent,  superheating  surface 
445  cu.  ft.  furnace  volume. 


Number  of  Test        

41 

42 

43 

44 

45 

Date  of  Test    1919 

Aug    14 

Aug    15 

Aug    15 

Aug   21 

Aug   21 

Lodi 

No   and  size  of  Sprayer  Plate   .  . 

3-47-2 

3-40-2 

3-40-2 

3-104 

3  25-1    1 

Duration  of  Test  —  Hours  

6 

4 

4 

2.5 

3.58 

Steam  Pressure  —  Ib.  per  sq.  In.  .  .  . 
Steam  Temperature  —  Deg   F 

178.2 
453  6 

178.4 
466  9 

177.9 
482  3 

186.2 
504  9 

192.1 
530  4 

Superheat  —  Deg  F 

74  7 

88  0 

103  6 

122  6 

146   1 

Feed  Temperature—  Deg.  F  
Factor  of  Evaporation        

71.9 
1  2394 

70.35 
1  2484 

72.3 
1  2549 

70.8 
1  2675 

71.6 
1  2798 

Oil  Pressure  at  Burners  Ib.  per  sq. 
in          

169.7 

120.3 

194  7 

193  2 

188  7 

Oil  Temperature  at  Burners  —  Deg. 
F 

250  7 

252  6 

248  2 

258  6 

232  7 

Total  Oil  Burned  —  Ib            .  . 

7016 

6245 

8171 

6558 

12663 

Oil  burned  per  hour  —  Ib 

1169  8 

1561 

2042  8 

2623  2 

3537  1 

Oil  Burned  per  hour  per  burner  —  Ib. 

389.8 

520.4 

680.9 

874.4 

1179.0 

Temperature  of  Flue  Gases  —  Deg. 
F 

413 

443 

485 

523 

6  16 

Temperature  of  Room  Deg.  F  

81 

86 

89 

93 

97 

Draft    Inside    Damper  —  Inches    of 
Water       

24 

40 

71 

77 

72 

Draft  in  Furnace  —  Inches  of  Water 
Air    Pressure   in    Duct  —  Inches    of 
Water 

.14 
22 

.18 
44 

.24 
75 

.21 

1  82 

.17 
3  64 

CO2                                    

13  77 

13  71 

13  53 

13  41 

13  70 

O             3rd  Pass     

2  26 

2  30 

2  61 

2  94 

2  65 

CO 

05 

06 

04 

o 

05 

Total  Water  Fed  Boiler  —  Ib  
Total  Water  From  and  at  212  deg. 
—  Ib          

87515 
108466 

77733 
97041 

98928 
124145 

77098 
97722 

139722 
178816 

Water  Per  Hour  From  and  at  212  — 
Ib          

18078 

24260 

31036 

39089 

49947 

Actual  Evaporation  per  Ib.  of  oil  — 
Ib                   ... 

12  47 

12  45 

12   11 

11  76 

11  03 

Equiv.  Evaporation  fr.  and  at  per 
Ib.  of  oil—  Ib  

15  46 

15  54 

15   19 

14  60 

14   12 

Water  fr.  and  at  per  sq.  ft.  of  H.  S. 

4.02 
524  0 

5.39 
703  2 

6.89 
899  6 

8.69 
1133  0 

11.10 

1447  7 

Per  Cent    Rating 

116  4 

156  3 

199  9 

251   8 

321   7 

Efficiency  —  Per  cent   

81   80 

81  41 

79  05 

77  91 

75  29 

Gravity  of  Oil-Baum6  

15  3 

15  3 

19  5 

15  3 

17  0 

Per    cent.    Moisture   in   Oil 
B.t.u.  Per  Lb.  of  Oil  

18340 

18530 

18650 

18560 

18200 

*From  paper  by  Darrah   Corbet  published  in  the  August,  1920,  Journal  of  the  Amer- 
can  Institute  of  Electrical  Engineers. 


ECONOMIES  OBTAINED  IN  OIL  BURNING  PRACTICE     359 


TUBES  DUSTED  AFTER  THE  FIRST  SET  OF  HEADINGS  AND  BOILER  OPERATED 
FOR  Six  DAYS  WITHOUT  FURTHER  USE  OF  THE  SOOT 
BLOWERS.     OIL  FUEL 


Draft 

Capac- 

ity 

Fur- 

Third 

Per 

Breech- 

C02, 

o, 

CO, 

Date,  1916 

nace, 

pass, 

cent,  of 

ing 

per 

per 

per 

in. 

in. 

rating, 

temp., 

cent. 

cent. 

cent. 

per 

deg.  F. 

cent. 

Mar  24  A.M.... 

0  08 

0  35 

145 

650 

15  5 

0  5 

0  0 

Mar  24.. 

T 

ubes  d 

usted 

Mar.  24,  P.  M  

0.07 

0.33 

143 

574 

14.5 

2.2 

0.0 

Mar  25.. 

0  08 

0  34 

141 

594 

14  7 

1  6 

0  0 

Mar.  27,  

0.07 

0.37 

144 

607 

15.0 

1.05 

0.0 

Mar  28  

0.08 

0.43 

146 

635 

14.1 

2.0 

0.0 

Mar  29.. 

0  08 

0  37 

142 

637 

14  9 

1  05 

0  05 

Mar.  30  

0.08 

0.40 

142 

668 

15.2 

1.0 

0.05 

may  be  shut  tight,  thus  materially  reducing  the  loss  of  heat  to 
the  chimney  during  this  period.  Tests  have  shown  that  the 
oil  required  to  keep  a  boiler  hot  in  this  manner  amounts  to  from 
1.5  to  3  per  cent,  of  the  quantity  of  oil  required  to  operate  the 
boiler  at  its  rated  capacity.  The  tighter  the  damper  the  less 
oil  will  be  required.  In  a  boiler  with  good  tight  dampers  the 
drop  in  steam  pressure  will  be  not  more  than  10  or  15  pounds 
per  hour. 

The  best  recorded  results  of  oil  burning  plants  are  those 
obtained  at  the  three  Arizona  plants  described  in  C.  R.  Wey- 
mouth's  paper  entitled  "Economy  of  Certain  Arizona  Steam  Elec- 
tric Power  Plants  Using  Oil  Fuel,"  presented  at  the-June,  1919, 
meeting  of  the  American  Society  of  Mechanical  Engineers. 
This  paper  shows  that  a  plant  having  6000  K.  W.  turbines  operat- 
ing with  a  steam  pressure  of  175  Ib.  and  10,0  deg.  superheat  and 
2  to  3  in.  absolute  back  presure  generates  from  257  to  294  kilowatt 
hours  per  barrel  of  oil.  Another  plant,  having  250  Ib.  steam 
pressure  and  150  deg.  superheat  and  1.66  in.  to  2.14  in.  absolute 
back  pressure,  generates  from  287  to  326  kilowatt  hours  per 
barrel  of  oil.  Monthly  boiler  room  records  of  the  former  plant 
show  combined  net  efficiency  of  boilers  and  economizers  of 
approximately  83  per  cent.,  which  corresponds  to  79^  per  cent, 
net  efficiency  for  the  boilers  alone. 


360  FUEL  OIL  AND  STEAM  ENGINEERING 

The  following  additional  data  on  the  economies  and  method 
of  operation  at  one  of  these  plants,  namely  the  New  Cornelia 
Copper  Company,  was  compiled  by  E.  A.  Rogers  who  was  for 
two  years  Chief  Engineer  in  charge  of  the  plant : 

ECONOMIES  IN  THE  NEW  CORNELIA  COPPER  COMPANY  PLANT 

Type  of  Equipment. — The  generating  equipment  consists  of 
two  General  Electric  turbo-generators  rated  at  7500  kilowatts  at 
80  per  cent,  power  factor.  The  generators  are  3-phase,  60 -cycle, 
2300-volt  at  1800  r.p.m.  The  turbines  are  designed  to  use 
steam  at  240  pounds  pressure  and  140  degrees  superheat. 

The  condensing  equipment  consists  of  Wheeler  surface  con- 
densers, Wheeler  dry  vacuum  and  centrifugal  hot  well  pumps. 
Duplicate  hot  well  pumps,  one  motor  driven  and  one  turbine 
driven,  are  provided  for  each  condenser.  Each  condenser  has 
its  own  motor-driven  centrifugal  circulating  water  pump  for 
supplying  the  cooling  water  from  the  pond. 

The  boiler  equipment  consists  of  five  Stirling  boilers  rated  at 
825  h.p.  each.  They  are  operated  at  a  pressure  of  255  pounds  and 
as  normally  operated  deliver  steam  at  110,  degrees  superheat. 
Being  equipped  with  asbestos  insulation  and  steel  casings,  radia- 
tion and  air  infiltration  losses  are  reduced  to  a  minimum.  The 
gases  leaving  the  boilers  pass  through  Green  fuel  economizers 
which  are  arranged  so  that  with  four  boilers  in  operation,  each 
economizer  takes  care  of  two  boilers.  Natural  draft  is  used  and 
as  the  air  temperatures  are  high  in  summer,  a  stack  220  feet 
high  is  necessary.  This  stack  is  of  reinforced  concrete,  double 
for  part  of  its  height,  and  the  tapered  construction  gives  not 
only  good  mechanical  proportions  but  a  pleasing  appearance. 
Feed  water  heaters  are  provided  which  utilize  the  steam  from 
the  rotative  dry  vacuum  pumps  and  feed  water  pumps  to  heat 
the  feed  water  before  it  goes  to  the  economizers.  The  pumps  for 
handling  the  feed  water  are  turbine  driven  centrifugals,  the  ex- 
haust steam  from  the  turbine  going  to  the  feed  heater. 

BOILER  EFFICIENCY 

The  firing  of  the  boilers  is  controlled  by  a  Moore  automatic 
regulating  system  which  is  one  of  the  main  contributing  factors 
in  the  maintaining  of  the  high  boiler  efficiencies  obtained  at  this 
plant.  The  furnaces  are  of  the  Hammel-Peabody  type  and  Ham- 


ECONOMIES  OBTAINED  IN  OIL  BURNING  PRACTICE    361 

mel  oil  burners  are  used.  That  the  automatic  control  of  the 
dampers  produces  excellent  results  is  shown  by  the  boiler  effi- 
ciencies maintained.  With  the  dampers  properly  set  the  regu- 
lator maintains  a  draft  condition  which  gives  almost  perfect 
combustion  as  shown  by  the  gas  analyzer,  the  per  cent,  of  CO2 
in  the  gases  leaving  the  boilers  being  maintained  between  limits 
of  13.0  per  cent,  and  14.5  per  cent.  The  following  figures  show 
the  boiler  room  results  for  the  month  of  December,  1919: 

Load  on  boilers  in  per  cent,  of  rating 91.0% 

Gross  boiler  plus  economizer  efficiency 84 . 5% 

Gross  boiler  efficiency 80 . 0% 

Amount  of  steam  used  for  atomizing  oil 1.0% 

Net  boiler  efficiency 79 . 0% 

These  percentages  do  not  take  into  consideration  the  additional 
amount  of  steam  used  for  atomizing  the  oil  with  hand  firing,  but 
refer  to  automatic  control  only.  When  the  boilers  were  fired  by 
hand  the  atomizing  steam  was  supplied  through  a  line  on  which 
there  is  no  flow  meter  and  consequently  accurate  data  on  this  item 
is  not  available.  It  has  been  the  writer's  experience  that  with 
hand  firing  the  atomizing  steam  will  vary  from  2.0  per  cent,  to 
4.0  per  cent,  of  the  steam  generated,  depending  on  the  skill  and 
experience  of  the  operator.  Observations  on  the  boilers  at  this 
plant  would  indicate  a  steam  consumption  of  at  least  2.0  per  cent, 
for  atomizing,  which  is  a  loss  of  1.0  per  cent,  over  the  amount 
shown  for  automatic  control. 

With  regard  to  the  efficiency  of  the  automatic  control  of  the 
firing  of  the  boilers  as  compared  with  hand  firing,  it  has  been 
found  that  the  boiler  room  efficiency  is  4  per  cent,  to  5  per  cent, 
higher  when  the  regulators  are  in  operation  than  when  firing  and 
damper  setting  are  done  by  hand.  The  comparison  has  been 
made  at  times  when  the  regulators  were  taken  out  of  service  for 
inspection  and  general  overhauling,  and  the  firing  and  regulating 
of  dampers  done  entirely  by  hand. 

OPERATION  OF  AUTOMATIC  REGULATORS 

The  automatic  regulators  do  not  relieve  the  fireman  of  all 
responsibility  in  connection  with  the  firing,  however,  for  it  is 
necessary  to  watch  the  burners  carefully  to  see  that  they  are 
working  properly.  It  occasionally  happens  that  a  burner  be- 
comes choked  or  partially  so  with  carbon,  which  reduces  the  Size 


362  FUEL  OIL  AND  STEAM  ENGINEERING 

of  the  flame.  This  results  in  a  considerable  amount  of  excess 
air  in  this  particular  boiler  and,  unless  the  burner  is  changed, 
may  result  in  a  serious  loss  in  efficiency.  The  fireman  must  be 
trained,  furthermore,  to  understand  the  value  of  the  gas  analysis 
in  its  relation  to  efficient  operation.  This  is  necessary  because 
it  is  essential  for  them  to  make  adjustments  on  the  main  damper 
regulator  to  compensate  for  changes  in  draft  conditions  due  to 
atmospheric  changes.  Thus,  for  instance,  if  the  dampers  are 
set  during  the  day  to  give  proper  combustion  and  at  night  the 
air  cools  down  considerably,  the  stack  draft  increases  and  more 
air  will  be  drawn  into  the  boilers  than  is  necessary.  When  the 
fireman  finds  that  this  condition  exists,  by  turning  a  hand  wheel 
and  tightening  a  spring  on  the  damper  regulator  the  dampers 
are  set  for  the  new  draft  conditions  and  automatically  take  care 
of  changes  in  load  as  before.  It  has  been  found  in  this  plant  that 
this  adjustment  for  changes  in  draft  due  to  atmospheric  changes 
is  a  very  important  part  of  maintaining  high  economies. 

MAINTAINING  ECONOMY 

In  order  to  obtain  a  maximum  of  effort  on  the  part  of  the  oper- 
ating force,  in  maintaining  the  proper  economies,  the  economy  is 
worked  out  for  each  watch  and  posted  daily.  The  rivalry  thus 
promoted  has  aided  materially  in  maintaining  good  operating 
results  in  the  plant.  The  results  thus  posted  every  day  are: 

Kilowatt-hours  generated. 

Barrels  of  fuel  oil  used. 

Pounds  of  water  evaporated. 

Kilowatt-hours  per  bbl.  of  oil. 

Pounds  of  water  per  pound  of  oil. 

The  equipment  used  to  obtain  this  and  other  data  is  as  fol- 
lows : 

For  accurately  measuring  the  fuel  oil  two  carefully  calibrated 
tanks  are  used,  it  being  possible  to  obtain  the  oil  consumption 
within  less  than  one-half  of  1  per  cent. 

A  Cochrane  V  notch  meter  in  the  feed  water  heater  and  a 
Venturi  meter  on  the  feed  water  line  to  the  boilers  give  the  amount 
of  water  evaporated.  A  General  Electric  steam  flow  meter 
gives  the  amount  of  steam  used  for  atomizing  the  fuel  oil. 

The  boilers  are  provided  with  draft  gauges,  superheated  steam 
thermometers,  flue  gas  thermometers  and  Uehling  C02  recorders, 


ECONOMIES  OBTAINED  IN  OIL  BURNING  PRACTICE    363 


Thermometers  are  also  provided  on  the  economizers  for  gases 
entering  and  leaving,  and  water  entering  and  leaving. 

Readings  are  taken  hourly  and  logged,  of  all  of  these  instru- 
ments, and  thus  it  is  an  easy  matter  to  locate  any  losses  of  ef- 
ficiency which  may  occur. 

As  the  town  of  Ajo  is  situated  in  the  desert,  extreme  tempera- 
tures prevail  in  the  summer  months  and  consequently  much  lower 
economies  are  obtained  during  this  period.  The  circulating 
water  for  the  condensers  gets  very  warm,  this  resulting  in  a 
material  loss  in  vacuum.  The  vacuum  is  also  influenced  by  scale 


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FIG.  211. — In  the  summer  the  circulating  water  for  the  condensers  gets  very 
warm,  and  the  vacuum  is  influenced  by  a  scale  forming  in  the  condenser  tubes. 
Much  lower  economies  prevail  during  the  period  of  these  extreme  temperatures 
at  New  Cornelia  Copper  Co.'s  plant,  Ajo,  Arizona. 

forming  in  the  condenser  tubes,  but  this  loss  can  be  easily  reme- 
died by  cleaning  the  tubes  out  with  a  proper  cleaner.  To  de- 
termine when  it  is  necessary  to  remove  the  scale,  tests  are  run, 
from  which  a  heat  balance  for  the  condenser  can  be  worked  out. 
From  this  heat  balance  the  heat  transfer  through  the  tubes  can 
be  determined  and  when  this  figure  falls  below  a  certain  point 
the  tubes  are  cleaned. 

In  spite  of  the  very  low  vacuum  during  the  summer  months, 
fairly  good  efficiencies  can  be  obtained,  as  shown  by  the  load 
efficiency  curve.  During  February,  March  and  April  the  load 
was  very  low,  which  accounts  for  the  low  efficiencies  obtained, 


364 


FUEL  OIL  AND  STEAM  ENGINEERING 


when  the  vacuum  was  relatively  high.  During  the  first  twelve 
days  of  May  the  turbine  was  run  with  practically  no  load  except 
the  plant  auxiliaries,  but  the  plant  was  in  readiness  to  pick  up  at 
any  time  the  full  load.  This  accounts  for  the  low  efficiency 
shown  for  this  month,  the  average  for  the  last  nineteen  days  being 
303  kw.-hr.  per  bbl.  In  June  the  load  was  increased  practically 
to  normal  conditions,  and  these  conditions  held  until  in  December 
the  load  was  again  reduced  with  a  corresponding  drop  in  effi- 
ciency. All  efficiencies  shown  or  given  in  terms  of  kw-hr.  per 
bbl.  of  oil  are  net,  all  power  used  in  the  plant  being  deducted 
from  the  total  generation  before  figuring  the  efficiency. 


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FIO.  212. — Economy  curve  showing  the  relation  between  the  load  and  B.t.u. 
supplied  per  kw.  hour  during  the  year  1919,  at  New  Cornelia  Copper  Co.,  Ajo, 
Arizona. 

The  best  economy  obtained  by  the  plant  during  1919  was  for 
the  last  eleven  days  of  January.  During  this  period  the  load 
averaged  8085  kw.  The  temperature  of  the  circulating  water 
was  68.8  degrees,  and  the  vacuum  1.28  in.  absolute.  The  average 
net  economy  was  323.1  kw.-hr.,  per  barrel.  Individual  days 
showed  as  high  as  327  kw.-hr.  per  barrel,  and  individual  shifts 
better  than  330  kw.-hr.  per  barrel,  but  these  results  are  not  as 
accurate  as  those  taken  over  a  longer  period.  The  economy 
curve  showing  the  relation  between  the  load  and  B.t.u.  supplied 
per  kilowatt  hour  generated  is  calculated  from  the  results 
actually  obtained  in  the  plant  during  the  year  1919.  In  some 


ECONOMIES  OBTAINED  IN  OIL  BURNING  PRACTICE     365 


cases  on  the  low  loads  correction  was  made  for  circulating  water 
temperature,  as  the  loads  occurred  when  the  water  was  about 
75°.  At  the  higher  ratings,  however,  the  curve  corresponds  to 
the  actual  existing  temperatures  and  conditions. 

Notwithstanding  the  fact  that  with  a  cooling  pond  and  spray 
nozzles  it  is  necessary  to  pump  the  circulating  water  against  a 
considerably  greater  head  than  should  ordinarily  be  necessary 
in  a  sea- water  plant,  the  power  used  by  the  auxiliaries  compares 
quite  favorably  with  plants  of  the  latter  type.  The  average 
amount  of  power  used  by  the  auxiliaries  during  1919  was  3.2 


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FIG.  213. — Load  efficiency  curve  at  plant  of  New  Cornelia  Copper  Co.  All 
efficiencies  shown  or  given  in  terms  of  kw.  hour  per  barrel  of  oil  are  net,  all 
power  used  in  the  plant  being  deducted  from  the  total  generation  before  figur- 
ing the  efficiency. 

per  cent,  of  the  total  generation  and  under  normal  full  load 
this  figure  is  2.75  per  cent.  The  auxiliaries  include  the  circulat- 
ing water  and  hot-well  pumps,  air  washers  for  generators,  econo- 
mizer scrapers,  motor-generator  for  switch  control  power,  and 
station  lights. 

MOTOR-GENERATOR  SETS 

In  addition  to  the  generating  equipment  the  plant  contains 
the  motor-generator  sets  which  furnish  the  direct  current  for  the 
electrolytic  deposition  of  copper.  There  are  four  of  these  sets, 
three  being  in  continuous  operation  and  the  fourth  a  spare. 
Each  set  consists  of  a  2400-h.p.  synchronous  motor  direct-con- 


366 


FUEL  OIL  AND  STEAM  ENGINEERING 


nected  to  an  850-kw.  direct  current  generator  on  each  end  of  the 
shaft.     These  generators   are   rated   at  5000  amperes  at    170 


P 


FIG.  214. — Exterior  view  of  power  plant  of  New  Cornelia  Copper  Co.,  Ajo, 
Arizona,  showing  tapered  construction  of  reinforced  concrete  stack  220  feet 
high. 


FIG.  215. — This  cooling  pond  measures  150  by  400  feet  and  is  one  of  the 
largest  in  the  country.  Each  condenser  in  the  plant  has  its  own  motor-driven 
centrifugal  circulating  water  pump  for  supplying  the  cooling  water  from  the 
pond. 

volts,  and  as  normally  operated  carry  the  full  load  current  at  160 
to  170  volts.    Thus  with  three  units  in  service  there  is  a  total 


ECONOMIES  OBTAINED  IN  OIL  BURNING  PRACTICE    367 

load  of  30,000  amperes  at  160  to  170  volts  on  the  d.c.  side.  As 
this  load  is  continuous  for  24  hrs.  a  day  it  gives  the  plant  a  very 
high  load  factor,  at  times  94  per  cent,  and  averaging  about  90 
per  cent.  This  aids  materially  in  maintaining  high  economies. 
The  motors  being  synchronous  make  it  possible  to  keep  the 
power  factor  at  98  to  99  per  cent.,  which  has  made  it  possible 
to  carry  peak  loads  of  10,000  kw.  on  one  of  the  main  generators. 


FIG.  216. — Turbine  room,  New  Cornelia  Copper  Co.,  Ajo,  Ariz.,  showing  an 
auxiliary  exciter  unit  in  the  foreground,  one  of  the  turbo-generators,  and  four 
motor  generator  sets  in  the  background.  Three  of  these  sets  are  in  continuous 
operation,  and  carry  a  total  load  of  30,000  amperes  at  160  to  170  volts  on  the 
d.c.  side,  24  hours  a  day. 

Accompanying  illustrations  show  the  power  plant,  cooling 
pond  and  interior  of  the  plant.  The  cooling  pond  is  one  of  the 
largest  in  the  country,  being  150  ft.  wide  by  400  ft.  long.  The 
turbine  room  is  shown,  an  auxiliary  exciter  unit  made  by  the 
Allis-Chalmers  Company  appearing  in  the  foreground,  then  one 
of  the  turbo-generators,  and  in  the  background  the  four  Westing- 
house  motor-generator  sets. 


CHAPTER  XLII 
MISCELLANEOUS  OIL  BURNING  TESTS 

TESTS  AT  LONG  BEACH  STEAM  PLANT 

General. — The  following  report  covers  a  series  of  tests  con- 
ducted on  the  boilers  at  the  Long  Beach  Steam  Plant  of  the 
Southern  California  Edison  Company,  and  was  compiled  by 
H.  L.  Doolittle,  steam  power  plant  specialist  for  the  company. 
These  tests  extended  over  a  period  of  approximately  10  mos. 

Description  of  Plant. — The  Long  Beach  Steam  Plant  is  located 
at  the  Long  Beach  Inner  Harbor,  Long  Beach,  California,  and 
consists  of  the  following  equipment: 

No.  1  Unit — placed  in  operation  August  20,  1911,  consisting  of 
one  12,000-kw.  General  Electric  Co.  vertical  Curtis  Turbo- 
generator running  at  750  r.p.m.;  eight  777.5-h.p.  Stirling  boilers; 
duplex  feed  pumps;  turbine  driven  exciter;  engine  driven  centrif- 
ugal circulating  pump;  all  auxiliaries  steam  driven  excepting 
spare  hot  well  and  oil  drain  pumps  which  are  motor  driven. 

No.  2  Unit — placed  in  operation  February  2,  1913,  consisting  of 
one  15,000-kw.  General  Electric  Co.  vertical  Curtis  turbo- 
generator running  at  750  r.p.m.;  eight  777.5-h.p.  Stirling  boilers; 
steam  turbine  driven  centrifugal  feed  pumps;  turbine  driven 
exciter;  steam  turbine  driven  centrifugal  circulating  pump;  all 
auxiliaries  steam  driven  excepting  spare  hot  well  and  oil  drain 
pumps  which  are  motor  driven. 

No.  3  Unit — placed  in  operation  March  30,  1914,  consisting  of 
one  20,000-kw.  General  Electric  Co.  vertical  Curtis  turbo- 
generator running  at  750  r.p.m.;  eight  850-h.p.  Stirling  boilers 
fitted  with  Sturtevant  economizers;  motor  driven  exciter;  cen- 
trifugal boiler  feed  pumps;  centrifugal  circulating  pump;  all 
auxiliaries  being  motor  driven  with  the  exception  of  the  fuel  oil 
pumps  which  are  duplex  steam  pumps. 

All  boilers  are  equipped  with  four  Hammel  oil  burners  and 
B.  &  W.  U  tube  superheaters. 

All  units  operate  at  the  normal  pressure  of  225  Ib.  gauge  and 
125°F.  superheat. 


MISCELLANEOUS  OIL  BURNING  TESTS  369 

Method  of  Testing. — In  general  all  tests  extended  over  a 
period  of  from  7  to  8  hrs.,  all  observations  being  taken  every 
15  min. 

All  temperatures,  except  the  stack  temperatures,  were  taken 
with  mercurial  thermometers  calibrated  by  means  of  a  standard 
thermometer. 

All  pressure  gauges  were  calibrated  with  the  dead  weight  gauge 
tester.  Small  differences  in  pressure  and  small  pressures  were 
measured  with  mercury  U  tubes. 

Stack  temperatures  for  boiler  tests  were  measured  by  means 
of  a  resistance  thermometer  consisting  of  copper  wire  installed  in 
the  path  of  the  flue  gases.  The  resistance  of  this  wire  was 
obtained  by  taking  a  cold  reading  after  the  wire  was  installed. 
Temperatures  were  calculated  from  the  variation  in  the  resistance 
of  the  wire.  It  was  hoped  that  this  method  of  measuring  the  flue 
gas  temperature  would  be  very  accurate  inasmuch  as  the  wire  was 
strung  back  and  forth  across  the  flue  so  as  to  measure  the  average 
gas  temperature.  It  was  found,  however,  that  this  method  of 
measurement  gave  more  or  less  erratic  results  which  must  be 
due  to  the  varying  velocities  of  the  gas  flowing  past  the  wire. 
It  appears  that  in  general  this  method  would  give  results  that 
are  too  low,  on  account  of  the  fact  that  the  gas  in  the  upper  part 
of  the  flue  is  the  hottest  and  travels  with  the  greatest  velocity. 
It  is,  however,  believed  that-  this  method  gives  as  accurate 
results  as  can  be  obtained  by  means  of  a  thermometer  or  a 
pyrometer  as  either  of  these  methods  would  be  subject  to  the 
same  error  due  to  varying  gas  velocities.  The  ideal  method  of 
measuring  gas  temperature  appears  to  be  some  system  by  which 
the  product  of  the  velocity  of  the  gas  by  its  temperature  could 
be  averaged  for  various  sections  of  the  flue. 

Flue  gas  analyses  were  made  with  a  portable  Orsat  flue  gas 
testing  apparatus. 

Fuel  oil  was  weighed  on  a  5000-lb.  Fairbanks-Morse  portable 
platform  scale  calibrated  in  place  against  standard  weights. 

The  steam  required  for  atomizing  the  oil  in  the  burners  was 
measured  by  installing  an  orifice  between  two  flanges  in  the 
steam  pipe.  The  drop  in  pressure  through  this  orifice  was 
measured  by  means  of  a  mercury  U  tube.  The  orifice  was 
calibrated  by  condensing  the  steam  flow  through  the  orifice 
during  a  given  period  of  time  in  a  tank  of  water  and  measuring 
the  increase  in  weight. 

24 


370  FUEL  OIL  AND  STEAM  ENGINEERING 

Four  samples  of  oil  were  taken.  These  samples  were  composee 
of  small  amounts  of  oil  taken  approximately  every  hour  from  ths 
oil  being  fed  to  the  boilers.  The  analyses  of  the  oil  sampled 
were  made  by  Wrana  King  &  Company,  Chemists,  Los  Angeles. 

The  water  evaporated  during  the  boiler  tests  was  obtained  by 
correcting  the  total  water  weighed  to  the  boilers  for  feed  pump 
leakage,  amounting  to  75  Ib.  per  hour. 

In  all  tests  the  water  evaporated  was  corrected  for  the  height 
of  the  water  in  the  boiler  gauge  glasses,  the  deduction  amount- 
ing to  670  Ib.  per  inch. 

BOILER  TESTS 

A  series  of  nineteen  boiler  tests  was  conducted  on  the  boilers 
of  the  No.  3  unit  in  order  to  determine  the  most  economical  load 
at  which  the  boilers  should  be  operated.  In  the  test  on  a  single 
boiler,  one  boiler  of  a  battery  was  used  with  the  other  boiler  of 
the  battery  shut  down.  This  necessarily  increased  the  radiation 
losses  of  the  boiler  being  tested  but  it  was  much  easier  to  conduct 
the  test  in  this  manner  on  account  of  the  fact  that  one  economizer 
is  installed  to  take  care  of  two  boilers.  The  tests  made  on  two 
boilers  were  made  with  both  boilers  in  one  battery  operating. 

In  all  of  the  boiler  tests  complete  readings  of  the  temperatures, 
pressures  and  water  fed  to  the  boilers  were  taken  so  as  to  deter- 
mine the  efficiency  of  the  boiler  alone  and  also  the  combined 
efficiency  of  the  boiler  and  economizers.  All  of  the  boilers  tests, 
excepting  that  made  on  March  9,  1915,  were  made  with  Hammel 
oil  burners. 

The  first  ten  tests  were  conducted  on  the  boiler  with  the  furnace 
as  originally  installed  by  the  manufacturer.  The  remaining 
tests  were  made  on  a  boiler  with  the  furnace  rebuilt  to  accommo- 
date three  instead  of  four  burners.  In  addition  to  rebuilding 
the  furnace,  the  boiler  for  the  last  series  of  tests  had  a  slight 
modification  in  the  baffling  of  the  rear  pass.  This  modification 
consisted  in  removing  two  rows  of  12-in.  tile  directly  in  front  of 
the  damper  opening. 

In  this  series  of  boiler  tests  we  endeavored  to  determine  the 
efficiency  of  both  the  boiler  and  economizer  at  different  loads, 
the  maximum  and  minimum  loads  that  the  boiler  was  capable  of 
carrying,  the  effect  of  hot  water  entering  the  economizer,  the 
efficiency  of  the  boiler  during  a  swinging  load,  and  also  the  oil 


MISCELLANEOUS  OIL  BURNING  TESTS 


371 


required  to  bring  the  boiler  up  to  header  pressure  after  being 
shut  down  for  several  hours. 

Boiler  Efficiency. — Fig.  217  shows  the  gross  boiler  effici- 
ency obtained  for  the  various  tests  plotted  against  combined 
economizer  and  boiler  horse  power.  These  curves  show  that 
the  efficiency  is  practically  constant  between  55  per  cent,  and 
130  per  cent,  of  boiler  rating.  The  curves  drawn  through  the 
points  represent  a  fair  average  of  all  the  tests.  Any  great 
departure  from  these  curves  is  generally  for  an  obvious  reason; 
for  instance,  it  is  seen  that  the  efficiency  for  the  swinging  load, 
also  for  the  test  of  the  boiler  starting  up  cold,  fall  very  far  below 

%  Rating 
20  30  40  50  60   70  80  90  100  110  120  130  140  150  16&  170  180  190  200 


030 
O 


10 


3  Burner  Boiler 
0  =  4       .•  "         #. 

©=  Starting  U"p  Cold*"  18 
tt=  2  Boilers 

Small  figures  indicate  number 

of  burners  operating 


0      100    200    300    400    500    COO    700    800    900    1000  1100  1200  1300  1400  1500  1600 

Econ.  &  Boiler  H.P. 

FIG.  217. — Boiler  tests  at  the  Long  Beach  Plant  of  the  Southern  California 
Edison  Company,  showing  the  relationship  of  gross  efficiency  and  total  rating 
at  which  boiler  is  operated. 

the  average  efficiency.  The  points  representing  the  tests  during 
which  hot  water  was  fed  to  the  economizer  also  result  in  a  low 
efficiency.  Two  of  the  three  tests  on  two  boilers  fall  about  3 
per  cent,  below  the  average  efficiency.  It  is  expected  that  the 
combined  efficiency  for  two  boilers  operating  on  one  economizer 
would  be  less  than  for  a  single  boiler  operated  on  the  same  eco- 
nomizer on  account  of  there  being  just  half  the  economizer  sur- 
face available  per  boiler.  It  is  also  noticeable  that  the  tests  on 
the  low  loads  which  were  made  with  fewer  burners  operating, 
gave  better  efficiency  than  those  with  a  larger  number  of  burners. 
This  would  indicate  that  it  would  be  more  economical  to  operate 
the  boilers  on  light  loads  with  either  one  or  two  burners  instead 
of  with  all  four  burners. 


372  FUEL  OIL  AND  STEAM  ENGINEERING 

The  tests  of  the  boiler  equipped  with'  three  burners  gave 
practically  the  same  efficiency  as  those  conducted  on  the  boilers 
equipped  with  four  burners.  It  was  also  possible  to  obtain  the 
same  maximum  capacity  with  three  as  with  four  burners.  This 
would  indicate  that  there  would  be  some  advantage  in  having 
future  boilers  equipped  with  three  burners  as  it  would  make  one 
less  burner  per  boiler  to  be  kept  in  repair.  There  is  a  possible 
disadvantage  in  reducing  the  number  of  burners,  however  in 
that  the  four  burner  furnace  would  permit  one  burner  becoming 
inoperative  without  reducing  the  capacity  of  the  boiler  or 
necessitating  the  immediate  installation  of  a  good  burner. 

The  curve  showing  the  combined  efficiency  of  boiler  and 
economizer  shows  the  tendency  of  the  economizer  to  flatten  out 
the  efficiency  curve  at  high  load.  This  largely  compensates 
for  the  rapid  decrease  in  boiler  efficiency  as  the  load  is  increased. 
In  general  the  economizer  adds  from  9  to  12  per  cent,  to  the 
boiler  efficiency  and  at  the  same  time  increases  the  boiler  capacity 
approximately  12  per  cent. 

After  conducting  the  first  ten  tests  on  the  boiler  as  originally 
installed,  it  was  found  that  the  loss  in  draft  in  passing  over  the 
rear  baffle  in  front  of  the  damper  opening  was  .2  in.  at  140  per 
cent,  rating.  This  had  the  effect  of  reducing  the  available  draft 
on  the  furnace  and  thus  limiting  the  boiler  output.  It  was, 
therefore,  decided  to  remove  the  two  top  rows  of  rear  baffle  tile 
leaving  only  one  row  above  the  damper  opening.  After  making 
this  change  it  was  found  that  the  available  draft  was  greatly 
increased  thereby  making  possible  much  higher  loads  on  the 
boiler. 

Figure  218  shows  the  draft  required  at  the  damper  for  the  vari- 
ous loads  on  the  boiler  after  removing  the  two  top  rows  of 
the  rear  baffle.  From  this  curve  it  is  seen  that  a  definite  draft 
is  required  for  a  given  load  on  the  boiler,  or  for  a  given  amount 
of  oil  burned  per  hour.  It  is  rather  surprising  to  note  that  the 
boiler  can  be  operated  up  to  70  per  cent,  of  rating  with  a  positive 
pressure  on  the  damper. 

Stack  Temperatures.— Figure  219  shows  the  stack  tempera- 
tures obtained  for  the  gases  out  of  the  boiler  and  also  out  of  the 
economizer.  These  curves  show  only  the  result  obtained  during 
the  tests  on  the  reconstructed  boiler.  The  temperatures  taken 
during  the  first  ten  tests  were  found  to  be  unreliable  on  account 
of  the  location  of  the  wires  used  in  measuring  the  temperature. 


MISCELLANEOUS  OIL  BURNING  TESTS 


373 


The  curves  show  that  the  temperature  of  the  gases  leaving  the 
boiler  vary  from  400°  to  700°,  while  the  temperatures  leaving  the 
economizer  are  between  180°  and  265°.  It  is  noticeable  that  the 
economizer  has  a  tendency  to  maintain  the  stack  temperature 
at  a  fairly  constant  value.  As  stated  before,  it  is  questionable  if 
the  readings  taken  for  stack  temperature  represent  the  actual 
values.  It  is,  however,  believed  that  they  give  a  good  indication 
of  the  variation  in  temperature  as  well  as  the  actual  amount. 


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1000                                  2000                                3000                                400 

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.  —  • 

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Note  :     One  row  of  tile  only  in  rear  baffle 
Draft  measured  inside  of  damper 

^ 

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0  10  20  30  40  50  60  70  80  90  100  110  120  130  140  150  ICO  170  180  190  200 

%  Rating 

FIG.  218. — A  relationship  of  total  draft  at  the  damper  with  the  oil  consumed 
per  hour  and  also  compared  with  the  percentage  of  rating  at  which  the  boiler  is 
operated.  Note  that  the  draft  is  measured  inside  of  the  damper. 

Oil  Consumed. — Figure  220  shows  the  oil  burned  for  different 
loads  on  boiler  and  economizer.  It  is  seen  that  these  curves 
are  practically  a  straight  line  passing  through  zero  between  30  per 
cent,  and  150  per  cent,  of  rating  on  the  boiler.  This,  there- 
fore, indicates  that  the  boiler  operates  at  a  practically  constant 
efficiency  between  these  loads.  This  agrees  with  the  result 
shown  on  Fig.  217. 

This  matter  of  constant  efficiency  over  a  wide  range  of  load 
has  a  practical  bearing  on  the  operation  of  the  plant  in  that  it 


374 


FUEL  OIL  AND  STEAM  ENGINEERING 


would  enable  the  plant  to  be  operated  at  light  loads  on  several 
boilers.  The  boilers  would  then  be  ready  to  pick  up  additional 
load  on  short  notice. 


0       10     20     30     40     50      08     70     80     90     100   110   120    130   140   150   ICO    170    180 
%     Rating    Boiler 

FIG.  219. — Stack  temperatures  in  their  relationship  with  the  rating  at  which 
the  boiler  is  operated,  both  with  and  without  economizer. 


35UIT 

3000- 

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Rating 

100    200   300   400    500  600    700  800  900   1QQQ  1100 1200 1300 1400 1500 1COO 
Boiler  H.P.  of  Boiler  &  Econ. 

FIG.  220. — The  pounds  of  oil  per  hour  shown  in  relationship  with  boiler  h.p.  of 
boiler  and  economizer  combined. 

Steam  to  Burners. — The  steam  used  by  the  burners  was  ac- 
curately measured  by  means  of  calibrated  orifices,  the  difference 
in  pressure  across  the  orifices  being  measured  by  mercury  U 


MISCELLANEOUS  OIL  BURNING  TESTS 


375 


tubes.  After  making  several  attempts  to  find  some  relation 
between  the  steam  required  for  atornization  and  oil  burned  or  the 
load  on  the  boiler,  it  finally  appeared  that  the  steam  required 
was  practically  proportional  to  the  number  of  burners  operating. 
Figure  221  was  therefore  prepared  to  show  the  amount  of  steam 
per  pound  of  oil  fired  in  relation  to  the  number  of  pounds 
of  oil  burned  per  hour  per  burner.  The  curve  shown  is  an 
equilateral  hyperbola  which  would  represent  a  constant  amount 


w  0 


a 

I 

.30 


.20 


.10 


Note.'  Curves 


uilat 


drawn  are 


H — h 


ral  hyperbolas 


0      100    200   300  400    500  600  700   800    900  1300  1100  1200 13001400 

^  Oil  per  Hour  pisy  Burner 

FIG.  221. — Steam  to  burners  utilized  in  furnace  operation  shown  in  relation- 
ship with  the  oil  per  hour  per  burner.  Note  the  interesting  result  obtained  is 
that  the  curves  are  thus  shown  to  be  equilateral  hyperbolas. 

of  steam  used  per  burner  regardless  of  the  amount  of  oil  burned. 
It  is  seen  that  the  points  approximately  follow  this  curve. 
The  amount  of  steam  varies  from  0.11  Ib.  to  1  Ib.  of  oil,  when 
the  burner  is  handling  1400  Ib.  of  oil  per  hour,  to  0.4  Ib.  of 
steam  to  1  Ib.  of  oil  with  the  burner  handling  400  Ib.  of  oil  per 
hour.  From  this  it  is  seen  that  a  saving  in  steam  for  atomization 
could  be  affected  by  operating  the  boiler  with  a  smaller  number  of 
burners. 

Pressure  Loss  in  Superheater. — In  order  to  determine  the 
pressure  loss  through  the  superheater  a  mercury  U  tube  was 


376 


FUEL  OIL  AND  STEAM  ENGINEERING 


connected  across  the  two  superheater  headers  and  observations 
were  taken  at  frequent  intervals  for  one  hour  periods.  Figure  222 
shows  the  results  of  these  tests  and  from  this  curve  it  is  seen 


rop  Thru.Suphtr?%" 

!-•  N>  CO  *»  d 

^ 

—  ^ 

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^ 

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^ 

^^ 

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***^rr 

M      0      10     20     30     40      50     GO     70     80     90    100   110    120   130    140    150   160    170    180 

%  Rating  of  Boiler 

FIG.  222. — Pressure  loss  through  the  superheater  in  its  relationship  with  the 

rating  of  the  boiler. 

that  the  drop  across  the  superheater  varies  uniformly  with  the 
load  on  the  boiler.  The  drop  at  170  per  cent,  of  rating  was 
found  to  be  only  3.6  Ib.  per  sq.  in. 


16 
15 
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500  H 


400 


200 


+.10  0  .10  .20  .30 

Draft  of  Damper 

FIG.  223. — A  relationship  showing  the  varying  draft  of  a  boiler  when  operated 
at  105  per  cent,  rating  in  its  relationship  with  draft  at  the  damper  and  the  tem- 
peratures of  the  stack. 

Varying  Draft. — Four  2  hr.  tests  were  made  on  one  boiler 
operated  at  a  constant  load  of  about  105  per  cent,  of  rating.  In 
these  tests  the  total  draft  at  the  damper  was  varied  from  zero 


MISCELLANEOUS  OIL  BURNING  TESTS 


377 


to  0.3  in.  and  the  effect  of  this  varying  draft  on  CO2  and  stack 
temperatures  was  noted. 

Figure  223  shows  the  results  of  these  tests.  From  these  curves 
it  is  seen  that  CO2,  which  is  an  indication  of  the  completeness 
of  combustion,  varies  from  8.5  per  cent,  for  the  0.32  in.  draft  to 
14.7  per  cent,  for  the  0.02  in.  draft.  From  Fig.  218  we  find  that 
the  draft  required  for  105  per  cent,  rating  is  .07  in.,  this  draft 
corresponds  to  13.2  per  cent.  CC>2  from  the  curves  on  Fig.  223. 
The  average  of  the  CO2  obtained  on  all  of  the  tests  for  the 


10     20    30    40    50     60    70     80    90    100  110    120   130  140  150  1GO  170  180  190  200 
Pressure  Steam  to  Burner  Header  *  Gauge 

FIG.  224. — A  relationship  showing  the  effect  of  varying  the  steam  header  pres- 
sure with  the  steam  and  oil  pressures  at  the  burner. 

boiler  equipped  with  four  burners  was  14.0  per  cent,  and  for 
the  tests  of  the  boiler  equipped  with  three  burners,  13.4  per  cent. 
It  is  therefore  seen  that  the  curve  obtained  for  the  tests  on 
varying  draft  agree  very  closely  with  those  obtained  during  the 
other  tests. 

It  is  also  apparent  from  these  tests  that  the  excess  air  varies 
directly  with  the  draft.  The  excess  air  under  normal  operation 
at  this  load  should  amount  to  20  per  cent,  corresponding  to  0.07 
in.  draft.  The  excess  air  will,  however,  be  increased  to  80  per 
cent,  by  increasing  the  draft  to  0.30  in.  This  gives  a  good  indica- 
tion of  the  unnecessary  loss  that  would  result  from  operating 


378  FUEL  OIL  AND  STEAM  ENGINEERING 

the  boiler  at  drafts  greater  than  those  required  to  give  proper 
combustion. 

Ratio  of  Oil  and  Steam  Pressures. — A  short  run  was  made  to 
determine  the  effect  of  varying  steam  pressure  on  the  steam 
and  oil  pressures  at  the  burner.  Pressure  gauges  were  installed 
on  the  burner  s^ide  of  the  regulating  valves  so  as  to  give  the  actual 
pressure  of  the  oil  and  steam  at  the  burner  tip. 

Figure  224  shows  the  results  of  simultaneous  readings  of  the 
pressures  on  the  steam  and  oil  headers  and  also  the  pressures 
of  the  steam  and  oil  at  the  burner.  During  this  test  the 
steam  header  pressure  was  varied  while  all  other  regulating 
valves  were  left  unchanged.  These  curves  show  very  clearly 
that  with  an  inside  mixing  burner,  such  as  the  Hammel,  the  oil 
pressure  at  the  burner  is  affected  to  a  great  extent  by  any  change 
in  the  steam  pressure. 

The  boiler  test  made  on  Jan  4, 1915  consisted  of  three  runs  made 
with  different  ratios  of  steam  and  oil  header  pressures.  These 
pressures  on  steam  and  oil  headers  were  respectively,  148  lb., 
50  lb.;  122  lb.,  41  lb.;  102  lb.,  41  lb.  The  combustion  during 
these  tests  appeared  to  be  practically  constant  as  the  CO2  varied 
only  0.32  per  cent.  There  was  also  very  little  difference  noted 
in  the  boiler  efficiency  showing  that  variation  in  oil  and  steam 
pressure  ratios  within  certain  limits,  have  practically  no  effect 
on  efficiency. 

Radiation  Test. — On  March  24,  1915  a  6  hr.  run  was  made  to 
determine  the  amount  of  oil  required  to  keep  up  full  steam 
pressure  with  the  boiler  cut  off  of  the  header.  In  this  test  a 
small  burner  having  an  oil  slot  %  m-  wide  was  used.  This 
burner  was  operated  at  intervals  as  required  to  keep  the  boiler 
pressure  within  the  limits  of  199  lb.  to  212  lb.  It  was  required 
to  operate  the  burner  a  total  of  2  hr.  and  57  min.  out  of  the  6  hr. 
and  there  was  used  223  lb.  of  oil  or  an  average  of  37  lb.  of  oil 
per  hour.  This,  therefore,  represents  the  radiation  losses  on 
boilers  kept  up  to  header  pressure  but  not  delivering  any  steam. 
It  is  evident  that  the  radiation  loss  would  be  somewhat  greater 
than  this  with  the  boiler  operating  under  normal  conditions  on 
account  of  the  higher  furnace  temperature. 

Swinging  Load. — On  March  18, 1915  a  seven  hour  test  was  made 
on  one  boiler  to  determine  the  efficiency  on  a  fluctuating  load. 

During  this  test  the  load  varied  from  approximately  90  per 
cent,  to  140  per  cent,  of  rating  and  for  42  min.  during  the  noon 


MISCELLANEOUS  OIL  BURNING  TESTS  379 

hour  the  fires  were  shut  down  completely.  The  results  of  this 
swinging  load  test  show  that  the  boiler  efficiency  was  approxi- 
mately 8  per  cent,  lower  than  the  combined  efficiency  of  boiler 
and  economizer,  and  approximately  6  per  cent,  lower  than  the 
corresponding  efficiency  obtained  under  normal  operation. 

Starting  up  Cold. — In  order  to  determine  the  amount  of  oil 
required  to  bring  a  cold  boiler  up  to  header  pressure,  a  run  was 
made  on  March  13,  1915  on  a  boiler  that  had  been  shut  down 
for  48  hours. 

The  water  in  this  boiler  just  before  the  test  was  at  a  tempera- 
ture of  148°.  The  boiler  was  brought  up  to  header  pressure  in 
62  min.  after  the  time  of  starting  and  during  the  period  1497  Ib. 
of  oil,  or  190  gal.  were  burned.  It  was  also  noted  that  the  water 
in  the  gauge  glass  rose  7^  in.  from  the  time  of  starting  until  the 
time  of  obtaining  header  pressure.  The  pressure  in  the  boiler 
started  to  rise  25  min.  after  the  beginning  of  the  test. 

TESTS    ON  FLOW  OF  OIL  THROUGH  BURNERS 

The  authors  are  indebted  to  Mr.  C.  R.  Weymouth,  Chief 
Engineer  of  Chas.  C.  Moore  &  Company,  for  the  following  de- 
scription and  results  of  tests  made  some  years  ago  on  the  flow  of 
crude  oil  through  orifices  and  oil  burners,  and  the  relative  steam 
and  oil  pressures  at  the  burners. 

INFLUENCE   OF  LOAD   ON   PRESSURES   OF   OIL  AND  ATOMIZING 
STEAM  IN  Oil  BURNERS 

Very  little  information  has  been  published  concerning  the  oil 
pressure  to  operate  oil  burners  at  different  rate  of  firing,  or  the 
steam  pressure  necessary  to  give  proper  atomization  with  a  mini- 
mum quantity  of  steam.  In  the  average  plant,  hand  controlled, 
the  oil  pressure  is  maintained  at  a  constant  pressure  by  means  of 
a  pump  governor,  and  the  supply  of  oil  to  the  burners  is  controlled 
at  each  burner  by  the  burner  oil-throttle  valve,  and  similarly  the 
supply  of  steam  to  burners  by  the  burner  steam-throttle  valves. 
In  times  past  engineers  have  debated  the  advisability  of  carrying 
higher  or  lower  of  pressures  at  the  pumps,  as  influencing  the 
economy  of  firing  the  boiler,  without  stopping  to  think  that  any 
surplus  in  pressure  over  and  above  that  necessary  to  force  the 
oil  through  the  burner  orifice,  must  be  overcome  by  the  friction 
of  the  oil-throttle  valve,  and  that  unless  the  load  on  the  burner 


380 


FUEL  OIL  AND  STEAM  ENGINEERING 


or  the  rate  of  oil  firing  changes,  any  increase  in  pressure  at  the 
pump  above  the  necessary  minimum,  has  no  effect  whatsoever 
on  the  performance  of  the  burners,  or  the  pressure  between  the 
burner-throttle  valve  and  the  tip  of  the  burner. 

Also,  it  is  not  generally  known  that  a  comparatively  low  steam 
pressure  furnishes  all  of  the  steam  necessary  for  atomizing  oil 
at  the  lighter  loads,  and  that  the  maximum  steam  pressure  at  the 
burner,  generally  speaking,  can  be  considerably  less  than  the  boiler 
pressure.  From  this  fact  it  is  apparent  that  unless  the  steam- 
burner  throttle  valves  are  closely  regulated  a  large  waste  in 
steam  is  permissible,  corresponding  to  the  difference  between  the 
steam  pressure  necessary  to  atomize  the  oil  at  a  given  load,  and 
the  maximum  or  boiler  steam  pressure. 

TESTS  WITH  OIL  BURNERS 

With  the  present-day  high  price  of  fuel,  and  the  special  effort 
that  is  now  being  given  towards  the  conservation  of  fuel  and  other 


1COO  2COO  3000 

Lbs.Oil  per  Hour 

FIG.  225. — Chart  showing  the  flow  of  oil  through  orifices  of  stated  diameter 
at  different  temperatures.  It  is  to  be  noted  that  for  a  given  temperature  and 
orifice,  the  rate  of  flow  is  almost  directly  proportionate  to  the  pressure. 

resources,  it  is  thought  that  a  brief  review  of  ce'rtain  test  data  will 
be  of  interest  to  fuel  oil  users.  The  test  data  given  is  taken  from 
a  report  to  Chas.  C.  Moore  &  Company,  Engineers,  dated  July 
1,  1907,  by  G.  Chester  Noble,  then  assistant  professor  of  electrical 
engineering,  University  of  California.  The  data  from  these 
tests  was  the  basis  of  the  initial  design  of  the  Moore  Automatic 
Fuel  Oil  Regulating  System,  by  Chas.  C.  Moore  &  Company, 
Engineers.  It  happens  that  all  of  the  burners  tested  were  of  the 


MISCELLANEOUS  OIL  BURNING  TESTS 


381 


external  atomizing  type,  the  particular  burners  selected  being 
those  which  were  available  for  the  work,  without  any  preference 
as  to  make  of  burner.  The  oil  burned  at  that  date  was  practically 
crude  oil,  which  was  somewhat  heavier  in  gravity  and  consid- 
erably more  viscous  than  the  topped  oil  now  generally  used  for 
fuel  purposes. 

Figure  225  gives  data  as  to  the  flow  of  oil  through  orifices  of 
stated  diameter  at  different  temperatures.  The  specific  gravity 
and  viscosity  of  the  oil  were  not  observed  at  the  time.  It  will 
be  seen  that  the  plotted  points  fall  practically  on  a  straight  line, 
indicating  a  flow  of  oil  for  a  given  temperature  and  a  given  orifice 


140 
120 
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irves  showing  the  Flow  of  Oil  Through  an 
Orifice  against  a  Constant  Resistance 
at  Various  Temperatures 
so  Curve  showing  Steam  Pressure  Required 
to  Atomize  the  Oil 
Diani.of  Orifice  =5/32 
Constant  Resistance  being  Three  Leah/ 
Oil  lJurners 

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1000                    1500                    2000 
30         Lbs.of  Oil  per  Hr. 

FIG.  226. — Curves  showing  the  flow  of  oil  through  an  orifice  and  length  of 
piping  at  various  temperatures.  To  this  is  added  a  curve  showing  the  steam 
pressure  required  to  atomize  the  oil.  Diameter  of  orifice — %2  ^n-  A  constant 
resistance  was  maintained  against  three  oil  burners  connected  in" parallel. 

nearly  proportionate  to  the  pressure;  and  it  is  interesting  to  note 
that  with  the  oil  then  used  a  pressure  gauge  in  the  burner  line 
so  placed  as  to  record  the  pressure  on  the  oil  burner  orifice,  was 
a  rough  index  as  to  the  rate  of  flow  of  oil,  or  the  relative  load  on 
the  boiler. 

Figure  226  gives  additional  data,  being  the  flow  of  oil  through  an 
orifice  and  length  of  piping,  including  also  the  resistance  of  three 
oil  burners  connected  in  parallel.  The  curve  also  shows  the 
steam  pressure  necessary  for  atomizing  the  oil  used  by  the  burn- 
ers. It  will  be  observed  that  the  curves  of  oil  pressure  and  of 
steam  pressure  are  nearly  straight  lines.  The  tests  for  both  of 
the  above  curves  were  made  at  the  University  of  California. 


382 


FUEL  OIL  AND  STEAM  ENGINEERING 


Figure  227  gives  tests  showing  oil  pressure  and  steam  pressure 
at  burner  at  the  old  Third  Street  Plant  of  the  Pacific  Light  and 
Power  Company,  Los  Angeles. 


90 
80 
70 

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Curves  shewing  Results  of  Tests 
on 
Leahy  Oil  Burner 
at 

Pacific  Light  &  Power  Go's  Plant, 

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100   200 


800 


900   1CCO 


400    500   COO    700 
Lbs  of  Oil  per  Hr,  per  Burner 

FIG.  227. — Curves  showing  relationships  of  steam  and  oil  pressure  at  burner 
during  a  test  on  a  Leahy  Oil  Burner  at  the  old  Third  St.  plant  of  the  Pacific 
Light  and  Power  Company,  Los  Angeles. 


Curves  shewing  Kesults  of  Tests 

on 
Leahy  Oil  Eurner 

at 
Oakland  Gas  Light  &  Heat  Co's  Plant 


60 
56 
52 

S48 
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£  23 

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0     2    4    6    8    10  12  14  1C  18  20  22  24  26  28  30  32  34  36  38  40  42  44  46  48  CO 
Oil  Pressure  at  Pump 

FIG.  228. — Test  data  showing  oil  and  steam  pressure  at  burner  at  the  Oakland 
Gas  Light  and  Heat  Company's  Plant,  now  station  C  of  the  Pacific  Gas  and 
Electric  Company. 

Figure  228  gives  similar  data  at  the  plant  of  the  Oakland 
Gas  Light  &  Heat  Company,  Oakland,  now  Station  "C,"  Pacific 
Gas  &  Electric  Company. 


MISCELLANEOUS  OIL  BURNING  TESTS 


383 


Curves  showing 

the 

Steam-Oil  Pressure  Helation 

for  all  the  Tests  in 

this  report 


0     10     20 


20    40    50    CO     70     80     90    ICO  110  120 
Steam  Pressure-  Lbs.  per  Sq.In. 


FIG.  229.  —  Curves  showing  the  steam-oil  pressure  relation  for  all  tests  reported. 
Note  that  all  these  curves  represent  practically  straight  lines. 


170 
ICO 
ICO 
140 
130 
I    120 
*    110 
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Curves  showing  the  Flow  of  Oil  TLrouth  an 
Orifice  against  a  Constant  Resistance 
With  Various  Initial  Pressures 
D  lam.  of  Orifice   x  5/j6 
Constant  BesUtauce  being  Three 
LeaLy  Oil  Burners 

5CO 


2&00 


1COO  1500 

Lbs. of  Oil  per  Hour 

FIG.  230. — The  influence  of  temperature  on  the  flow  of  oil  through  an  orifice 
against  a  constant  resistance  with  various  initial  pressures. 


384  FUEL  OIL  AND  STEAM  ENGINEERING 

Figure  229  gives  results  of  various  tests,  in  which  the  steam- 
pressure  and  the  oil-pressure  on  the  burner  are  the  two  variables. 
It  is  apparent  that  the  curves  represent  practically  straight  lines. 

Figure  230  shows  the  influence  of  temperature  on  the  flow  of 
oil  through  an  orifice,  the  pressure  difference  remaining  constant. 

PRACTICAL  APPLICATION  OF  TEST  DATA 

To  illustrate  the  application  of  the  above  data  in  the  design  of 
the  Moore  Automatic  Fuel  Oil  Regulating  System,  now  in  use  in 
a  number  of  prominent  plants  in  the  West,  it  should  be  stated, 
for  those  not  familiar  with  the  details  of  this  system,  that  it 
operates  on  the  principle  of  central  control  instead  of  individual 
control  of  the  burners  and  dampers.  The  oil  burners  and  valves 
are  left  wide  open,  or  nearly  so,  and  a  variable  oil  pressure  is 
maintained  in  the  oil-burner  header  to  given  an  equal  pressure 
at  all  burners,  the  pressure  varying  with  the  load,  controlled  auto- 
matically by  throttling  the  supply  of  oil  to  the  header,  to  main- 
tain a  nearly  constant  steam-boiler  pressure.  As  in  most  plants, 
burners  must  be  designed  to  handle  very  heavy  oil  and  also  to 
permit  heavy  overloads  on  boilers,  the  average  pressure  at  the 
burner  at  normal  loads  is  very  low  and  but  a  few  pounds.  To 
build  up  the  pressure  in  the  oil-to-burner  header,  and  to  prevent 
the  friction  in  the  header  causing  an  unequal  supply  of  oil  to  all 
burners,  a  resistance,  due  to  a  diamond-ported  regulating  cock, 
is  inserted  in  each  burner-branch  pipe  between  the  main  throttle 
valve  and  the  tip  of  the  burner  and  set  to  give  such  resistance  that 
the  pressure  in  the  header  at  normal  load  on  the  boilers  will  be 
20  or  30  Ib.  or  thereabouts,  depending  upon  operating  character- 
istics, etc.  Then  a  slight  pressure  drop  in  the  header  would  have 
little  effect  on  the  unequal  supply  of  oil  to  the  various  burners. 

The  oil  pressure  gauges  connected  to  this  header  are  located  in 
the  front  of  each  battery  of  boilers,  so  that  the  firemen  can  tell 
approximately,  from  the  reading  of  the  oil-pressure  gauge,  the 
relative  rate  of  firing  of  boilers. 

A  low  pressure  steam  header  is  similarly  connected  to  all 
burners,  but  generally  without  the  diamond  ported  valve  as  a 
resistance,  the  pressure  being  high  enough  without  this  resistance. 
The  supply  of  steam  from  the  main  boilers  to  the  low  pressure 
burner  header,  and  its  pressure,  are  controlled  by  means  of  a 
special  throttle  valve,  generally  known  as  a  chronometer  valve, 


MISCELLANEOUS  OIL  BURNING  TESTS  385 

and  this  chronometer  valve  is  in  turn  controlled  by  a  steam-to- 
burner  regulator  actuated  by  the  variable  oil  pressure  in  the 
oil-to-burner  main. 

If  the  curve  of  steam  and  oil  pressure,  as  mentioned  above,  is 
a  straight  line,  then  the  steam  pressure  is  equal  to  the  oil  pressure 
multiplied  by  a  coefficient  plus  a  constant.  At  one  plant  this 
relationship  was  found  to  be  such  that  the  steam  pressure  at  the 
burner  was  equal  to  the  oil  pressure  times  three,  plus  thirty; 
thus  at  rating  the  oil  pressure  was  20  Ib.  and  the  steam  pressure 
was  90  Ib.;  at  50  per  cent,  overload  the  oil  pressure  was  30  Ib. 
and  the  steam  pressure  was  120  Ib. ;  at  half  the  load  the  oil  pres- 
sure was  10  Ib.  and  the  steam  pressure  was  60  Ib. 


CHAPTER  XLIII 


PRESENT  STATUS  OF  OIL  BURNING  POWER  PLANT 

DESIGN 

The  present  shortage  of  hydro-electric  power  on  the  Pacific 
Coast  has  created  an  unusual  situation  in  that  the  demand  for 
power  is  so  great  that  steam  plants  intended  originally  to  act 
merely  as  standby  installations  and  to  assist  the  hydro-electric 


FIG.  231.— Oil  fields  and  oil  pipe  lines  of  California. 

systems  in  case  of  trouble  are  now  being  operated  at  full  capacity 
and  carrying  a  large  proportion  of  the  total  load.  Other  steam 
plants  are  being  planned,  and  those  already  under  way  are  being 

386 


OIL  BURNING  POWER  PLANT  DESIGN 


387 


rushed  to  completion  so  as  to  tide  over  the  emergency  fast 
becoming  acute. 

Fuel. — California  oil  is  the  fuel  that  is  used  almost  exclusively, 
along  the  Western  Coast.  However,  unless  its  production  is 
greatly  increased,  in  the  next  few  years  Mexican  oil  will  be 
introduced  into  California  as  it  has  been  in  Arizona,  Texas  and 
the  Atlantic  Coast.  Mexican  oil  is  generally  much  heavier, 
dirtier  and  more  viscous  than  California  oil.  Oil  in  the  Panuco 


FIG.  232. — Graphical  display  of  petroleum  production. 

field  runs  in  gravity  about  12°  Baume  and  is  so  viscous  that  it 
cannot  be  unloaded  from  a  car  without  being  heated  and  must 
be  kept  up  to  a  temperature  of  120°F.  (50°C.)  in  the  pipes  in 
order  to  keep  it  flowing.  It  is  therefore  necessary  to  use  large 
pipes,  covered  on  the  outside  and  containing  internal  heating 
pipes  through  which  steam  or  hot  water  is  passed.  Mexican  oil 
usually  contains  a  large  proportion  of  silt,  and  it  is  necessary  to 
provide  strainers  at  both  the  suction  and  discharge  of  pumps  as 


388 


FUEL  OIL  AND  STEAM  ENGINEERING 


well  as  at  the  burners.     To  burn  properly  it  must  be  heated  up 

to  190°F.  (90°C.)  and  in  somecases  even  as  high  as250°F.(110°C.) 

Natural  gas  is  now  being  used  in  Bakersfield  and  in  Los  Angeles. 

This  is  the  only  available  fuel  that  is  superior  to  fuel  oil.     It  has 


930 


FOOD  Pto&ucn 
FIG.  233. — Comparative  uses  of  crude  petroleum. 

all  the  advantages  of  oil,  and  in  addition  does  not  require  at- 
omizers or  bulky  storage  tanks  if  it  is  piped  direct  from  the  wells. 
Coal  is  used  quite  extensively  in  the  Pacific  Northwest,  both 
in  pulverized  form  and  stoker-fired.     In  California,  however, 


FIG.  234. — Comparison  of  coal  and  fuel  oil  production. 

there  is  no  coal  marketed  except  for  domestic  purposes.  If  oil 
continues  to  advance  in  price,  the  question  of  the  available  sup- 
ply of  coal  will  become  of  paramount  importance.  The  most 
promising  source  appears  to  be  the  Alaskan  coal  fields,  which  are 


OIL  BURNING  POWER  PLANT  DESIGN  389 

known  to  be  very  extensive  and  to  contain  coal  of  excellent 
quality.  Vast  developments  must  be  made,  however,  in  the 
way  of  transport  and  docking  facilities  before  Alaskan  coal 
becomes  available  in  quantities  sufficient  to  represent  a  factor  of 
importance  in  connection  with  power  developments. 

The  design  of  a  coal-burning  plant  differs  in  many  respects 
from  that  of  an  oil-burning  plant.  Boilers  must  be  set  higher  for 
coal  than  for  oil  so  as  to  provide  room  for  mechanical  stokers  or 
to  provide  ample  combustion  space  for  powdered  fuel.  A  base- 
ment under  the  boilers  is  required  for  handling  ashes.  The 
building  must  be  high  enough  to  allow  for  coal  bunkers  and  con- 
veyors above  the  boilers,  larger  smokestacks  are  necessary,  and 
forced-draft  apparatus  is  usually  required.  In  most  cases, 
therefore,  it  would  be  impracticable  to  change  over  existing  oil- 
burning  plants  to  coal-burning  plants,  although,  on  the  other 
hand,  it  is  an  easy  matter  tc  change  a  coal-burning  plant  to  an 
oil-burning  one. 

In  some  cases  oil-burning  plants  have  been  specially  designed 
with  a  view  to  converting  them  to  coal-burning  at  a  future  date. 
However,  since  it  is  impossible  to  anticipate  the  rapid  changes 
that  occur  in  engineering  practice,  the  extra  expense  involved  in 
thus  attempting  to  design  for  the  future  is  hardly  warranted. 

Another  fuel  used  quite  extensively  in  the  Northwest  is  the 
refuse  from  sawmills,  known  as  hog  fuel.  This  is  an  extremely 
cheap  fuel  if  used  close  to  the  mill.  Owing  to  its  bulk,  however, 
it  is  difficult  to  transport,  and  its  field  of  usefulness  is  therefore 
limited. 

LOCATION  OF    STEAM -ELECTRIC    POWER  PLANTS 

Economy  of  design  in  the  vast  hydro-electric  transmission 
lines  of  the  West,  in  which  steam-electric  generation  serves  as  an 
auxiliary,  necessitates  the  location  of  the  steam-electric  plant 
as  near  to  the  large  industrial  centers  as  possible.  This  reduces 
to  a  minimum  the  distance  through  which  the  steam-generated 
power  must  be  transmitted,  thus  avoiding  the  necessity  of  burn- 
ing extra  fuel  to  make  up  for  transmission  losses.  The  exact 
location  within  the  industrial  center  depends  mainly  on  the  four 
following  factors :  (a)  An  adequate  supply  of  water  for  condensing 
purposes;  (6)  access  to  deep  water,  to  enable  oil  to  be  delivered 
by  barge;  (c)  railway  facilities  for  the  delivery  of  machinery 
and  possible  delivery  of  fuel;  (d)  proximity  of  the  transmission 


390 


FUEL  OIL  AND  STEAM  ENGINEERING 


a 


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PH    fe 


o  a 

« 


II 


OIL  BURNING  POWER  PLANT  DESIGN 


391 


lines  through  which  power  is  delivered  from  the  hydro-electric 
system. 

A  large  interconnected  hydro-electric  system  may  have  one 
large  auxiliary  steam  plant  or  several  small  ones.  As  most  of 
the  hydro-electric  systems  in  the  West  have  grown  to  their 
present  huge  proportions  through  combinations  of  several  smaller 
systems,  in  the  majority  of  cases  there  are  several  steam  plants 
connected  to  each  system.  While,  if  properly  designed,  a  large 
single  plant  is  in  general  more  economical  to  operate  than  a 
number  of  small  plants,  the  distribution  losses  may  be  much  less 


FIG.  236. — Diagrammatic  representation  of  refining  the  product. 

in  the  latter  case.  The  question  of  economical  distribution  is, 
therefore,  a  very  important  factor  in  determining  both  the  size 
and  the  location  of  a  plant. 

SIZE  OF  STEAM  PLANT  UNITS 

The  size  of  turbine  selected  for  a  plant  of  given  capacity  de- 
pends largely  on  the  question  of  spare  units  required.  In  the 
ordinary  isolated  steam  plant  it  is  an  axiom  that  in  order  to  in- 
sure continuity  of  service  it  is  necessary  to  have  enough  spare 
units  to  provide  for  repairs,  adjustments,  cleaning  of  condensers, 
and  any  other  of  the  many  causes  that  may  necessitate  the  shut- 
ting down  of  the  main  unit.  If  the  units  are  too  large  this  spare 
requirement  results  in  too  expensive  a  plant.  For  instance,  if 


392  FUEL  OIL  AND  STEAM  ENGINEERING 

the  plant  capacity  is  to  be  30,000  kw.  and  it  is  considered 
essential  to  have  at  least  one  spare  unit,  the  plant  may  consist 
of  two  30,000  kw.  machines,  three  15,000  or  four  10,000  kw. 
machines.  It  is  seen  at  once  that  for  the  same  plant  capacity 
with  one  machine  shut  down,  the  first  case  has  an  installed 
capacity  of  60,000  kw.,  the  second  case  45,000  kw.  and  the 
third  case  40,000  kw.  Since  the  cost  of  the  plant  is  approxi- 
mately proportional  to  the  installed  capacity  it  is  obvious  that  the 
selection  of  too  large  a  unit  results  in  excessive  first  cost. 


FIG.  237. — The  condenser  and  a  portion  of  the  42  inch  discharge  salt  water 
pipe  for  the  new  15,000  kw.  turbo  generator,  station  A,  San  Francisco,  Pacific 
Gas  and  Electric  Company. 

In  the  case  of  steam  plants  that  are  interconnected  with  a 
large  hydroelectric  system,  the  necessity  for  spare  units  is  not  so 
great,  as  it  is  always  possible  to  take  the  load  off  one  plant  tem- 
porarily and  carry  it  on  another.  In  such  plants  the  size  of  unit 
may  be  as  large  as  the  system  will  stand — that  is,  it  must  not  be 
so  large  as  to  cripple  the  system  when  it  is  shut  down.  The 
largest  single  unit  on  the  Pacific  Coast  at  the  present  time  is 
20,000  kw.,  although  machines  as  large  as  45,000  kw.  in  single 
units  have  been  built  and  are  operating  in  the  east. 

The  size  of  the  boiler  unit  is  also  affected  by  the  necessity 


OIL  BURNING  POWER  PLANT  DESIGN 


393 


of  having  enough  spare  boilers  to  permit  frequent  cleaning  and 
repairs.  It  is  desirable  in  any  central  station  to  have  at  least  4 
or  6  boilers.  In  the  East  many  plants  have  boilers  up  to  1,500 
h.p.  or  2,000  h.p.  each,  but  on  the  Pacific  Coast  600  h.p.  to  800 
h.p.  is  the  maximum.  For  oil  burning  the  best  results  are 
obtained  with  boilers  having  a  relatively  large  combustion  cham- 
ber, and  the  present  tendency  is  to  raise  boilers  higher  than  for- 
merly so  as  to  increase  the  furnace  volume  and  enable  the 
boilers  to  be  forced  to  high  capacities.  Oil-burning  boilers  have 
not  as  yet  been  forced  to  such  high  overloads  as  has  been  done  in 


FIG.  238.— The  new  turbo-unit  of  15,000  kw.,  station  A,  Pacific  Gas  and  Electric 
Company,  San  Francisco. 

Eastern  cities  with  coal-burning  boilers.  Capacities  of  200  per 
cent,  of  rating  have  been  obtained  with  steam  atomizing  burners, 
and  a  recent  plant  on  the  Atlantic  Coast  firing  Mexican  oil  with 
mechanical  atomizing  burners  has  operated  up  to  300  per  cent,  of 
rating.  Mechanical  atomizing  burners  produce  a  softer  flame 
that  is  less  damaging  to  brickwork  than  the  steam  atomizing 
burner,  and  give  a  higher  boiler  efficiency  at  high  overloads, 
owing  to  the  more  perfect  combustion  maintained  when  firing 
large  quantities  of  oil  in  furnaces  of  limited  volume.  They  re- 
quire strong  forced  draft,  however,  and  the  power  required  for 


394  FUEL  OIL  AND  STEAM  ENGINEERING 

this  as  well  as  the  extra  steam  used  for  heating  and  pumping 
tends  to  offset  these  advantages. 

Economizers  have  not  made  as  much  headway  in  oil  burning 
plants  as  in  coal  burning  plants.  This  is  largely  due  to  the 
fact  that  owing  to  the  small  amount  of  excess  air  required  with 
oil  burning,  there  is  less  heat  in  the  gases  leaving  the  boiler,  and 
hence,  less  necessity  for  economizers.  At  present  prices  of  fuel 
oil  it  would  undoubtedly  pay  to  install  economizers  in  any  plant 


FIG.  239. — Typical  view  of  auxiliary  apparatus  installed  in  Pacific  Coast 
power  plants.  Figure  shows  particularly  a  turbo  feed-water  pump  at  the  Long 
Beach  Plant  of  the  Southern  California  Edison  Company. 

that  is  to  be  operated  at  a  fairly  high  load  factor.  For  a  poor 
load  factor,  however,  and  especially  for  a  plant  that  is  expected 
to  act  during  most  of  its  life  as  a  standby  plant,  economizers  are 
not  considered  to  be  a  good  investment.  Where  economizers 
are  installed  it  is  necessary  to  either  increase  the  height  of  smoke- 
stack, or  provide  induced  draft  apparatus.  This  increases  the 
cost  of  the  economizer  installation,  and,  must  be  considered 


OIL  BURNING  POWER  PLANT  DESIGN 


395 


when  balancing  interest  and  other  fixed  charges  against  the 
increased  efficiency  resulting  from  the  economizers. 

The  modern  tendency  in  the  operation  of  central  steam  sta- 
tions is  toward  higher  steam  pressure  and  higher  superheat. 
Theoretically  in  any  heat  engine  the  maximum  efficiency  is 
obtained,  as  shown  in  the  Carnot  cycle,  by  having  the  tempera- 


FIG.  240. — Auxiliary  apparatus,  including  centrifugal  feed  pump  and  feed  water 
heater  at  Station  C.,  Pacific  Gas  and  Electric  Company,  Oakland. 

ture  at  which  the  heat  is  supplied  to  the  working  substance  uni- 
form at  the  highest  attainable  value  and  the  temperature  at 
which  heat  is  with-drawn  uniform  similarly  at  the  lowest  attain- 
able value.  With  steam  the  upper  temperature  range  may  be 
raised  either  by  increasing  the  pressure  or  by  increasing  the 
superheat,  or  both.  In  neither  case,  however,  is  the  upper  tem- 
perature range  uniform.  Increase  of  pressure  does,  however, 
carry  the  elevated  temperature  through  a  longer  part  of  the 
range  than  increase  of  superheat  and  thus  more  nearly  approaches 


396  FUEL  OIL  AND  STEAM  ENGINEERING 

the  condition  .for  maximum  efficiency  with  any  given  extreme 
upper  limit  of  temperature.  We  should  thus  expect  that  a 
given  extreme  upper  limit  of  temperature  reached  through  high 
pressure  arid  relatively  moderate  superheat  would  give  better 
conditions  for  economy  than  lower  pressure  and  higher  superheat. 


FIG.  241.  FIG.  242. 

FIGS.  241-242. — Economy  measuring  apparatus. 

The  temperature  and  pressure  of  the  steam  and  water  from  the  boiler  down  through  the 
condenser  need  careful  attention  in  the  economic  operation  of  the  modern  power  plant.  On 
the  left  is  exhibited  the  vacuum  gage,  barometer  and  thermometer  installed  between  the 
first  and  second  pass  of  the  steam  turbine.  Note  the  vacuum  of  29.15  in.  with  the  atmos- 
pheric barometer  reading  of  30.1  in.  To  the  right  may  be  seen  recording  meters  for  inlet 
and  outlet  temperatures  of  the  circulating  water,  steam  temperature,  vacuum  and  steam 

Eressure,  and  the  temperature  of  the  condensate.     The  Klaxon  horn  at  the  right  of  the  meter 
^ard  sounds  an  alarm  when  the  oil  pressure  accumulator  drops.     This  installation  is  at 
the  Long  Beach  Plant  of  the  Southern  California  Edison  Company. 

This  may  be  illustrated  by  the  following  example,  in  which  steam 
at  200  Ib.  pressure  and  200°F.  superheat  is  compared  with  steam  at 
300  Ib.  pressure  and  166°F.  superheat,  both  of  these  combinations 
giving  actual  temperature  of  superheated  steam  at  588°F. : 


OIL  BURNING  POWER  PLANT  DESIGN  397 

Pressure,  gage,  Ib.  per  sq.  in 200.0  300.0 

Temperature  saturated  steam,  deg.  Fahr 388 . 0  422 . 0 

Degree  of  superheat,  deg.  Fahr 200.0  166.0 

Temperature  superheated  steam,  deg.  Fahr 588 . 0  588 . 0 

Heat  per  Ib.  steam  (above  32  deg.)  B.t.u 1310.0  1300.0 

Heat   (above  32  deg.)  per  Ib.    steam  after  expanding 

adiabatically  to  1-in.  absolute,  B.t.u .  892 . 0  866 . 0 

Heat  available  per  Ib.  steam,  B.t.u 418.0  434.0 

Heat  utilized  at  75  per  cent,  efficiency,  B.t.u 313 . 0  325 . 0 

Moisture  in  exhaust  steam,  per  cent 9.2  11.4 

It  will  be  observed  from  the  above  comparison  that  while 
the  quantity  of  heat  present  in  the  initial  steam  in  the  two  cases 
is  practically  the  same,  the  heat  utilized  in  the  case  of  steam 
entering  the  engine  at  300  Ib.  pressure  is  about  4  per  cent,  more 
than  in  the  case  of  the  200  Ib.  pressure  steam.  In  actual  practice ! 
these  figures  would  be  slightly  modified  by  difference  in  effici- 
ency of  the  prime  mover  under  the  two  different  conditions. 
However  with  turbines  properly  designed  for  the  conditions 
under  which  they  are  to  operate  this  difference  would  be  small, 
and  may  be  neglected  in  the  present  discussion.  It  will  also  be 
observed  that  there  is  more  moisture  in  the  exhaust  steam  in  the 
case  of  300  Ib.  pressure  initial  steam  than  in  the  case  of  200  Ib. 
initial  steam.  This  means  that  there  will  be  less  work  to  be  done 
by  the  condenser  as  more  of  the  steam  is  already  condensed. 
This  results  in  a  still  further  advantage  to  the  higher  pressure 
steam.  On  the  Pacific  Coast  steam  pressures  up  to  200  Ib.  have 
been  used  for  many  years,  station  "A"  of  the  Pacific  Gas  & 
Electric  Company,  San  Francisco,  having  been  built  for  that 
pressure  in  1901. 

Within  the  last  two  or  three  years  higher  pressures  than  this 
have  been  adopted,  several  plants  having  been  built  for  boiler 
pressures  of  250  Ib.,  while  in  the  Eastern  states  plants  are  already 
in  operation  at  300  Ib.  pressure  and  pressures  even  as  high  as  500 
Ib.  are  being  talked  of  as  possibilities.  The  maximum  limit  to 
pressures  and  superheat  is  determined  at  the  present  time  by  the 
temperature  that  the  materials  of  construction  will  stand.  With 
present  steels  700°F.  is  about  the  limit.  This  limit  would 
be  reached  at  500  Ib.  pressure  and  230°F.  of  superheat.  The 
pressure  is  also  limited,  commercially,  by  the  extra  cost  in- 
volved as  it  is  possible  that  in  some  circumstances  the  fixed 
charges  on  the  extra  investment  required  for  the  high  pressure 
apparatus  may  neutralize  the  saving  effected. 


398 


FUEL  OIL  AND  STEAM  ENGINEERING 


In  the  modern  plant  both  steam  driven  and  electric  driven 
auxiliaries  are  used.  Steam  drive  is  always  the  cheapest  when- 
ever it  is  possible  to  make  use  of  the  exhaust  steam  for  heating 
purposes.  If  however,  the  exhaust  would  be  wasted  it  is  cheaper 
to  use  electric  driven  auxiliaries.  In  an  ordinary  plant  in  which 
all  the  auxiliaries  are  driven  by  steam  it  is  possible  to  utilize  all 
of  the  exhaust  steam  for  heating  the  feed  water  when  a  fairly 
heavy  load  is  carried  on  the  plant,  but  when  the  load  is  light 
there  is  less  feed  water  to  be  heated  and,  as  there  is  nearly  as 


FIG.  243. — Auxiliary  apparatus,  turbo  driven  at  the  Long  Beach  Plant  of  the 
Southern  California  Edison  Company. 

much  steam  used  by  the  auxiliaries  as  at  heavy  loads,  there  is 
bound  to  be  a  waste  of  steam.  It  is,  therefore,  more  economical 
to  use  steam  driven  auxiliaries  at  the  heavy  load  and  electric 
driven  auxiliaries  at  lighter  loads.  It  is  thus  desirable  to  install 
duplicate  auxiliaries  in  which  one  set  is  driven  by  steam  and  the 
other  by  electric  power.  The  electric  drive  is  not  quite  as  reliable 
as  steam  and  it  is  therefore  frequently  desirable  to  install  a 
separate  auxiliary  turbine  and  generator  to  generate  the  current 
required  by  the  auxiliaries.  If  this  is  done,  all  the  auxiliaries 
may  be  motor  driven.  At  times  of  heavy  load,  they  would  get 
their  current  from  the  auxiliary  generator  and  at  times  of  light 


OIL  BURNING  POWER  PLANT  DESIGN  399 

load  they  would  take  their  current  from  the  main  bus.  The 
exhaust  from  the  auxiliary  generator  would  thus  be  available  for 
heating  the  feed  water,  and  as  this  machine  could  be  run  merely 
as  a  standby  at  light  loads  there  would  be  no  exhaust  steam 
wasted.  This  system  has  been  used  to  advantage  at  the  Connors 
Creek  plant  of  the  Detroit  Edison  Company  and  other  stations 
in  the  east,  but  has  not  yet  been  introduced  on  the  Pacific  Coast. 
The  modern  tendency  is  to  eliminate  as  far  as  possible  all 
reciprocating  pumps  and  at  the  present  time  centrifugal  pumps 
are  used  in  all  cases  except  for  fuel  oil  and  lubricating  pumps 
where  the  reciprocating  type  is  still  used.  Steam  turbines  are 
used  in  preference  to  reciprocating  engines  even  in  cases  where 
slow  speed  is  desired  such  as  for  operating  circulating  pumps  for 
condensers.  In  such  cases  it  is  customary  to  provide  reduction 
gears  so  as  to  be  able  to  operate  the  turbine  at  high  speed  and 
the  pump  at  low  speed  thus  enabling  each  machine  to  operate  at 
the  speed  best  suited  to  highest  efficiency. 

AUTOMATIC  CONTROL 

As  economical  operation  of  a  plant  is  obtained  by  the  careful 
watching  of  all  details,  it  is  a  growing  conviction  that  personal 
control  under  trained  supervisors  is  the  one  way  to  produce  high 
economy.  This  is  especially  true  of  the  boiler  room,  and  it  is 
common  practice  in  the  best  plants  to  employ  a  combustion 
engineer  to  make  flue-gas  analyses  and  to  keep  continual  check 
on  the  boiler  efficiency.  There  is  a  tendency  toward  introducing 
automatic  control  into  the  fire  room.  Automatic  oil-fire  regula- 
tors have  been  placed  in  service  in  a  number  of  plants  on  the 
Pacific  Coast  and  increases  in  efficiency  as  high  as  3  or  4  per  cent, 
are  reported.  Another  tendency  at  the  present  time  is  to  equip 
the  plant  with  recording  meters  which  register  automatically  all 
important  elements  of  operation  throughout  the  full  twenty- 
four  hours  of  the  day.  It  was  formerly  the  custom  to  operate 
boilers  with  no  instruments  except  a  steam  gage,  but  it  is  now 
customary  to  install  steam-flow  meters  which  register  the  quantity 
of  steam  produced  by  the  boiler  and  the  quantity  of  steam  uesd 
by  the  burners,  and  air  meters  which  indicate  the  amount  of  air 
passing  through  the  boiler  settings.  These  instruments  are  of 
great  value  in  assisting  the  combustion  engineer  to  secure  maxi- 
mum efficiency  from  the  boiler  plant. 


APPENDIX  I 
ILLUSTRATIVE  PROBLEMS 

Problem  No.  1.  —  The  mean  effective  pressure  of  a  single-acting  oil  engine 
cylinder  under  test  is  found  from  an  indicator  card  to  be  43.9  Ib.  per  sq.  in.  ; 
the  cylinder  has  47.5  working  strokes  per  minute;  the  'diameter  of  the 
cylinder  is  30  .in.;  and  the  length  of  stroke  is  30  in. 

What  is  its  horsepower? 

Solution. 

By  reference  to  formula  for  horsepower  computation,  we  find  for 


P  =  43.9,  L  =       A  =  0.7854(30)2,  and  N  =  47.5  that  H.P.  =  = 

1^  3o,000 

43.9  X  2.5  X  706.9  X  47.5  _ 
33,000 

Problem  No.  2.  —  In  a  turbine  test  the  atmospheric  barometer  reduced  to 
the  32°F.  standard  of  measurement,  read  29.93  in. 

If  the  condenser  vacuum  reduced  to  the  same  standard  read  28.23  in.  of 
vacuum,  what  was  the  absolute  pressure  in  the  condenser? 

Solution. 

Barometer  for  day  ............................     29  .  93  in. 

Vacuum  maintained.  .  28.  23  in. 


Pressure  in  condenser  in  inches  of  mercury 1 . 70  in. 

14 . 696  Ib.  per  sq.  in.  =  29.92  in.  of  mercury. 
.  14.696      29.92 
X        ''    1.70 
X  =    09  QO  X  1.70  =  0.835  Ib.  per  sq.  in.  absolute  pressure  in  condenser. 

Problem  No.  3. — A  10,000  kw.  turbine  under  test  operated  with  a  gage 
reading  of  171.5  Ib.  per  sq.  in.  The  gage,  however,  read  one  pound  too  low. 
The  computed  absolute  pressure  was  found  to  be  187.2  Ib.  per  sq.  in. 

What  was  the  barometer  reading  for  the  day? 

Solution. 

Absolute  pressure =  187 . 2  Ib.  per  sq.  in. 

Corrected  gage  pressure  (171.5  +  1) =  172.5  Ib.  per  sq.  in. 


Atmospheric  pressure =     14 . 7  Ib.  per  sq.  in. 

14.696  =  29.92 

14.7  X 

29  96 
. " .  X  =      'gQg  X  14.7  —  29.93  in.  of  mercury  barometer  reading  for  the  day. 

400 


ILLUSTRATIVE  PROBLEMS  401 

Problem  No.  4. — A  corrected  atmospheric  barometer  reading  is  found  to 
be  29.942  in.  of  mercury  on  the  32°F.  standard. 
How  many  Ib.  per  sq.  in.  does  this  represent? 

Solution. 

To  convert  to  Ib.  per  sq.  in.  by  formula  in  the  chapter  on  pressures: 

Im      29.921 
P       14.696 
or  29.942  =  2.046  P 

. ' .  P  =  14.670  Ib.  per  sq.  in. 

Problem  No.  6. — A  corrected  barometer  reading  is  29.937  in.  of  mercury 
on  the  30-inch  vacuum  standard. 

What  is  the  pressure  in  Ib.  per  sq.  in.? 

Solution. 

•To  convert  to  Ib.  per  sq.  in.  from  formula  in  the  chapter  on  pressures: 

Im  =    30 
P       14.7 
or  29.937  =  2.041  P 

.'.P       =  14.668  Ib.  per  sq.  in. 

Problem  No.  6. — (a)  At  what  temperature  do  the  Fahrenheit  and  Centi- 
grade scales  read  the  same?  Fahrenheit  and  Reamur?  Centigrade  and 
Reamur? 

(b)  Assuming  the  absolute  zero  of  the  Fahrenheit  scale  to  be  459. 6°F. 
compute  the  absolute  zero  on  the  Centigrade  and  Reamur  scales. 

Solution. 

(a)  Fahrenheit  and  Centigrade. 
Relation  is  given  by  formula : 
F  -  32  =  9/5C 

When  the  scales  have  identical  numerical  readings,  then  F  =  C  =  X 
Substituting  in  formula 

X  -  32  =  9/5X 

4X  =  -  160  or  X  =  -40° 

/.  -40°F.  =  -  40°C. 
(Fahrenheit  and  Reamur. 
Relation  is  given  by  formula: 

F  -  32  =  9/47? 

Let  F  =  R  =  X,     then  X  -  32  =  9/4X 
5X  =  -  128,      or  X  =  -25.6 

. ' .  -  25.6°F.  =  -  25.6°R. 
Centigrade  and  Reamur. 
Relation  is  given  by  formula: 

C  =  5/4/2 
Let  C  =  R  =  X,     then  X 

4X  =  5X        or     X     =  0 
.  • .  0°C  =  0°R 
(6)  Absolute  zero  =  -  459.6°F. 

26 


•402  FUEL  OIL  AND  STEAM  ENGINEERING 

Let  us  substitute  this  value  of  F  in  the  general  relationship, 

F  -  32  =  9/5C 
and  we  have 

-459.6  -  32  =  9/5C 

9C  =  —  2458  or  C  =  -  273.1°  absolute  zero  on  Cent,  scale. 
Similarly  for  the  relationship 

F  -  32  =  9/4# 
we  have 

-  459.6  -32  =  9/4# 

9#=  -  1966.4 

R=  —218.049  =  absolute  zero  on  Reamur  scale. 

Problem  No.  7. — The  temperature  of  the  steam  entering  a  turbine  during 
a  test  was  found  to  be  521.2°F. ;  the  correction  for  stem  exposure  of  the  ther- 
mometer was  5.6°F.;  the  corrected  steam  gage  reading  172.5  Ib.  gage;  and  the 
atmospheric  barometer  read  14.7  Ib.  per  sq.  in. 
What  was  the  superheat  of  the  steam? 
Solution. 

Thermometer  reading  on  entering  steam  =       521 . 2° 

Correction  for  stem  exposure  =  +      5.6° 

True  temp,  of  steam  entering  turbine  =       526 . 8°F. 

Absolute  pressure  =  172.5  +  14.7  187.2  Ib. 

From  steam  tables  the  temperature  correspond- 
ing to  this  pressure  of  saturated  dry  steam        =       376 . 4°F. 
. ' .  Degrees  of  superheat  =  526 . 8°  -  376 . 4°        =  150 . 4° 
Problem  No.  8. — The  temperature  of  the  superheated  steam  entering  a 
turbine  during  a  test  was  found  to  be  544. 8°F.     The  pressure  of  the  steam 
in  the  main  was  182  Ib.  abs. 

What  was  the  superheat  of  the  steam  ? 
Solution. 

By  reference  to  Table  2  of  the  steam  tables  the  temperature  of  saturated 
steam  corresponding  to  182  Ib.  pressure  is  found  to  be  374.0°F.  Substract 
this  value  from  the  temperature  of  the  steam  entering  the  turbine  and  the 
result  will  be  the  degrees  of  superheat,  or 

544.8  -  374.0  =  170.8°F.  superheat 

Problem  No.  9. — Regnault's  classic  formula  for  total  heat  of  saturated 
steam  is: 

H  =  1091.7  +  0.305  (t  -  32) 

Compute  the  total  heat  of  saturated  steam  at  the  boiler  pressure  corre- 
sponding to  382.3°F. 
Solution. 
Substituting,  we  have 

H  =  1091.7  +  0.305  (382.3  -  32) 
=  1091.7  +  106.84 
=  1198.54B.t.u.  perlb. 
From  tables  H  =  1198.2 

1198.54  -  1198.2        0.34 


.*.  Error  = 


1198.2  1198.2 

=  0.0284% 


ILLUSTRATIVE  PROBLEMS  403 

Problem  No.  10. — Compute  the  total  heat  of  saturated  steam  at  382.3°F. 
by  the  formula: 

H  =  1150.3  +  0.3745  (t  -  212)  -  0.000550  (t  -  212)2 

Solution. — Substituting  the  value  of  temperature,  we  have 

H  =  1150.3  +  0.3745(382.3  -  212)  -  0.000550(382.3  -  212)2 
=  1150.3  +  63.78  -  15.95 
=  1198.13  B.t.u.  perlb. 
From  tables  H  =  1198.2 

1198.2  -  1198.13        0.07 
1198.2  ^Tl^ 

=  0.00585  per  cent. 

Problem  No.  11. — The  specific  volume  of  saturated  steam  is  represented  on 
page  104  of  Marks  and  Davis  Steam  Tables  by  the  formula: 

S  =  28.424  -  0.01650(2  -  320)  -  0.0000132(2  -  320)2 
Find  the  specific  volume  of  steam  for  t  =  382.3. 

Solution. — Substituting,  we  have 

S  =  28.424  -  0.01650(382.3  -  320)  -  0.0000132(382.3  -  320)2 
=  28.424  -  0.862  -  0.036 
=  29.525 

N.  B. — This  formula  evidently  does  not  check  up  at  all  for  this  tempera- 
ture, since  the  specific  volume  for  a  temperature  of  382.3°F.  is  2.279  from 
the  steam  tables. 

Problem  No.  12. — The  mean  specific  heat  of  steam  is  represented  mathe- 
matically on  page  92  of  Marks  &  Davis  Steam  Tables  by  the  formula : 

Cm  =  0.9983  -  0.0000288(2  -  32)  -  0.0002133(2  -  32)2 
What  is  the  mean  specific  heat  of  steam  for  t  =  382. 3°F.? 

Solution. — Substituting,  we  have 

Cm  0.9983  -  0.0000288  (382.3  -  32)  +  0.0002133(382.3  -  32)2 
=  0.9983  -  0.0000288(350.3)  +  0.0002133(350.3)2 
=  0.9983  -  0.0101  +  26.17 
=  27.1582  Mean  specific  heat. 

Evidently  a  mistake  is  made  in  translating  the  last  term  of  this  formula 
from  its  original  source,  for  it  should  be  .0000002133  (t  -  32)2.  On  this 
basis,  we  have  that 

Cm  =  0.9983  -  0.0101  +  .02617  =  1.0346 

In  the  steam  tables  the  heat  of  liquid  for  382°  is  355.0  B.t.u.  and  for  383° 
is  356.1  B.t.u.  Hence  the  mean  specific  heat  Cm  is  approximately  1.1,  which 
indicates  that  had  the  decimal  points  been  carried  further  the  specific  heat 
approaches  that  set  forth  in  the  above  correction. 

Problem  No.  13. — At  a  certain  central  station  there  are  four  773  boiler 
horsepower  Parker  boilers.  These  boilers  were  used  to  give  a  10,000  kw. 
load  at  the  terminals  of  a  turbine  which  has  an  over-all  efficiency  of  21  per 
cent.  What  was  the  percentage  of  overload  on  the  boilers? 


404  FUEL  OIL  AND  STEAM  ENGINEERING 

Solution. 

10  000 

f-^-  —  =  47,600  kw.  actually  taken  from  boilers  (neglecting  losses  in  steam 

U  .21 

mains). 
Since  l.hp.  =  .746  kw. 

A  7  f^f\f\ 

Q  '  fi     =  63,800  mechanical  horsepower  actually  taken  off  boilers. 

From  discussion  in  text,  we  have 

777.5  =  13  H  =  rat.o  Qf  boiler  horsepower  to  meChanical 
jUUU  , 

horsepower. 

485°  BL  h*     '  actually  taken  from  boiler' 


4  X  773  =  3092  Bl.  h.p.  rated  capacity. 

4850  -  3092 

•'•  --  onoo  --  X  100  =  56.8  per  cent,  overload. 
o(jyz 

Problem  No.  14.  —  A  Parker  boiler  under  test  operated  with  the  following 
conditions:  Steam  pressure  179.7  Ibs.  gage;  temperature  of  feed  water 
entering  boiler  was  123.4°F.;  barometer  for  the  day  read  30.1  inches  of 
mercury. 

Find  the  factor  of  evaporation  for:  (a)  steam  superheated  182°F.;  (6)  dry 
saturated  steam;  and  (c)  5  per  cent,  wet  steam. 

Solution. 

30  10          X 

otToo  =  IA  AQft  or  X  =  14.78  Ib.  per  sq.  in.  atmospheric  reading  of  day. 

£t\)t*ju      XTc.uyo 

Gage  reading  ............................       179  .  7    pounds 

Atmospheric  pressure.  :  ...................         14  .  78  pounds 

.'.  Abs.  pressure  of  boiler  ..................  =  194.  48  pounds 

From  Steam  Tables: 
hi    =  heat  of  liquid  at  absolute  boiler  pressure  ................         352  .  45 

LI    =  latent  heat  of  evaporation  at  absolute  boiler  pressure.  ...         845.2 

Hi  =  total  heat  of  steam  at  absolute  pressure  ................        1197.65 

/i2    =  heat  of  liquid  at  temperature  of  entering  feed  water  ......  91  .  3 

Ha  =  total  heat  of  superheated  steam  (194.48  Ib.  pressure  and  182° 

superheat) 
X    =  quality  of  steam 


) 

1297.99 

n.  . 

0  95 

V 

Hs 

-  hz   1297.99  -  91.3 

1206.69 

1  OAQ 

f  e 

T? 

Hl 

rO.4       970.4 
-  ht   1197.65  -  91.3 

1106.35 

—  1  1  A1 

.  .  . 

j?        h+XLi-hi  _  352.45  +0.95  X845.2  -  91.3  _  1065.25  _ 
970.4  970.4  =    970.4 

Problem  No.  15.  —  In  a  boiler  test,  the  temperature  of  the  feed  water 
entering  the  boiler  was  170.7°F.,  the  steam  pressure  was  144  pounds  gage, 
and  the  barometer  read  29.28  inches  of  mercury. 

Find  the  factor  of  evaporation  for:  (a)  dry  saturated  steam;  (6)  10  per 
cent,  wet  steam;  (c)  steam  superheated  125°F. 


ILLUSTRATIVE  PROBLEMS  405 


Solution. 
29  28  JC 


X  14'696  =  14<38  lb'  P6r  Sq-  m'  atmosPheric 

pressure. 


Boiler  gage  reading       =  144.00  Ib. 
Atmospheric  pressure    =     14  .  38  Ib. 


.'.  Abs.  boiler  pressure  =  158.38  Ib.  per  sq.  in. 
From  Steam  Tables: 

hi    =  heat  of  liquid  at  absolute  boiler  pressure  ...............   =  334.7 

Li    =  latent  heat  of  evaporation  at  absolute  boiler  pressure  ......   =  859  .  6 

Hi  =  total  heat  of  steam  at  absolute  boiler  pressure  ..........     =  1194.34 

h-i    —  heat  of  liquid  at  temperature  of  entering  feed'water  .....   =     138.57 

Hz  =  total  heat  of  superheated  steam  (158.38  Ib.  pressure  and 

125°  superheat)  ...................................   =  1263.  88 

ff  !  -  A,      1194.34  -  138.57      1055.77 
(0)  Fe  =  -970T  -9704"          =  ~9704T 

p    _  hi  +  XLl  -  A2      334.7  +  0.90  X  859.6  -  138.57  _  969.13  _ 
970.4  970.4  970.4   = 

0.999(vvhere  X  =  quality  of  steam) 
_        H8  -  hz      1263.88  -  138.57  _  1125.31 
^  ~~~  =  ~~ 


Problem  No.  16.  —  What  is  the  equivalent  evaporation  in  Ib.  of  water  per 
hr.  from  and  at  212°F.  if  the  water  fed  to  a  boiler  has  a  total  weight  of 
64,4941b.  and  the  factor  of  evaporation  is  1.193  Ib.? 

Solution.  —  By  applying  the  fundamental  formula  developed  in  the  text, 
we  have  at  once  equivalent  evaporation  from  and  at  212°F.  =  64,494  X 
1.193  =  76,950  Ib. 

Problem  No.  17.  —  Compute  the  factor  of  evaporation  for  a  boiler  generat- 
ing dry  saturated  steam  under  a  pressure  of  98.1  Ib.  per  sq.  in.  abs.  and 
receiving  its  feed  water  at  58.8°F. 

Solution.  —  Total  heat  of  saturated  steam  at  98.1  Ib.  abs.  =  1186. 
Heat  of  liquid  at  temperature  58.8°F.  =  26.88 
_  1186-  26.88 

~  970.4  ~ 

Problem  No.  18.  —  What  is  the  weight  of  equivalent  water  evaporated  to 
dry  steam  from  and  at  212°F.,  if  the  total  weight  of  water  actually  evapo- 
rated is  53,688  Ibs.  and  the  factor  of  evaporation  is  1.193? 

Solution.  —  Weight  of  equivalent  water  evaporated  to  dry  steam  from  and 
at  212°F.  =  53,688  X  1.193  =  64,150" 

Problem  No.  19.  —  The  equivalent  evaporation  of  a  boiler  under  test  is 
5940  Ibs.  of  water  per  hour,  and  the  total  heating  surface  of  the  boiler  is 
found  to  be  2031  sq.  ft. 

What  is  the  average  equivalent  evaporation  per  sq.  ft.  of  water  heating 
surface  per  hour? 


406  FUEL  OIL  AND  STEAM  ENGINEERING 

Solution. — The  average  equivalent  evaporation  per  sq.  ft.  of  water  heating 
surface  per  hour  is  evidently 

5940  _ 
2031       2'93 

Problem  No.  20. — The  equivalent  evaporation  of  a  boiler  under  test  is 
found  to  be  5940  Ib.  of  water  per  hour. 

What  is  the  boiler  horsepower  of  the  boiler? 

Solution. — By  definition 

Bl.  H.  P.  =  |^9  =  172.2 

Problem  No.  21. — The  rated  horsepower  of  a  boiler  is  given  by  the  builders 
as  210  Bl.  h.  p.     Under  test  172.2  Bl.  h.p.  were  actually  developed. 
What  was  the  percentage  of  boiler  capacity  developed? 

Solution. — Capacity  of  boiler  as  developed  in  percentage  is 
172.2 


210 


X  100  =  82  per  cent. 


Problem  No.  22.  —  What  is  the  equivalent  evaporation  per  Ib.  of  coal  as 
fired  in  a  boiler  under  test  when  the  weight  of  equivalent  water  evaporated 
to  dry  steam  from  and  at  212°F.  is  64,150,  and  the  total  weight  of  fuel  con- 
sumed as  fired  is  8012? 

Solution.  —  Equivalent  evaporation  per  Ib.  of  coal  as  fired  = 

64,150 
: 


Problem  No.  23.  —  From  a  Parker  boiler  test  covering  a  period  of  8  hrs., 
the  following  data  were  taken  : 

Steam  pressure  (gage)  ............................  185  .  3  Ib.  per  sq.  in. 

Atmospheric  barometer  ...........................  30  .  2  in. 

Temp,  of  water  entering  the  boiler  .................  169  .  1°F. 

Temp,  of  steam  leaving  the  superheater  drum  .......  527  .  °F. 

Specific  gravity  of  the  oil  at  60°F  ..................         0  .  9705 

Percentage  of  water  in  the  oil  .....................         0  .  7  of  1  % 

Calorific  value  of  oil  per  Ib  ...................  .....  18,752  B.t.u. 

Weight  of  oil  as  fired  .............................  15,084  Ib. 

Total  weight  of  water  fed  to  boiler  .................  205,277  Ib. 

What  is  the  degree  of  superheat  of  the  steam  leaving  the  superheater? 

30  2 

Solution.  —  Barometer  reading  =  30.2  in.  or  »    Q     =  14.83  Ib.  per  sq.  in. 


Steam  pressure  abs.  =  185.3  +  14.83  =  200.13  Ib.  per  sq.  in. 
From  tables  h  =381.9° 

Temp,  of  steam  leaving  superheater  drum  =  527°F. 

.'.527  -  381.9  =  145.1°  superheat 

Problem  No.  24.  —  What  is  the  gravity  of  the  oil  in  degrees  Baume  in 
Problem  23? 


ILLUSTRATIVE  PROBLEMS  407 

Solution. — For  light  liquids: 

140 

Sp.  gr.  = 


0.9705  = 


130  4-  Deg.  Baume" 
140 


130  +  Deg.  Baum6 
0.9705  (Deg.  Baume)  =  140  -  130  X  0.9705 

140  -  130  X  0.9705 
.-.  Deg.  Baume  = 09765- 

13.84 


0.9705 


=  14.26 


Problem  No.  25.  —  What  is  the  weight  of  the  oil  corrected  for  moisture  in 
Problem  23? 

Solution.  —  Percentage  of  water  in  the  oil  =  .7  of  1  % 

Wt.  of  oil  as  fired  ......................    =  15,084  Ib. 

.  '  .  15,084  X  0.007  =  105.6  Ib.  =  Wt.  of  water  in  oil 

Weight  of  oil  corrected  for  moisture  = 

15,084  -  105.6  =  14,978.4  Ib. 
Problem  No.  26.  —  What  is  the  factor  of  evaporation  in  Problem  23? 

Solution.  —  Factor   of   evaporation  =      *  Q  .  2    (for   superheated    steam) 

From  problem  23,  PI  =  200.13  Ib.  per  sq.  in.  and  145.1°  superheat. 

.  '  .  From  tables  Hs  =  1280.1  B.t.u. 

Also  from  problem  23  P2  =  14.83  Ib.  per  sq.  in. 

.  '  .  From  tables  h2  =  136.96  B.t.u. 

„  ,  ,.  1280.1  -  13696 

Factor  of  evaporation  =  —    —         - 

t7  4  U.4: 

=  1.178 

Problem  No.  27.  —  Determine  the  equivalent  evaporation  from  and  at 
212°F.  from  Problem  23. 

Solution.  —  Total  wt.  of  water  fed  to  boiler  =  205,277  Ib. 
Duration  of  test  ..........  ....................  =  8  hrs. 

Equivalent  evaporation  =  Water  evaporation  per  hr.  X  factor  of  evapo- 
ration = 

205,277  x  L17g  =  30  227  1K 

O 

Problem  No.  28.  —  What  is  the  boiler  horsepower  developed  in  A.S.M.E. 
rating  in  Problem  23? 

Solution. 

Equivalent  evaporation  from  and  at  212°F. 
H'P  34.5 


34.5 

Problem  No.  29.  —  What  is  the  equivalent  evaporation  from  and  at  212°F. 
per  Ib.  of  oil  as  fired  in  Problem  23? 


408  FUEL  OIL  AND  STEAM  ENGINEERING 

Solution—  Wt.  of  oil  as  fired  =  15,084  Ib. 


Wt.  of  oil  as  fired  per  hr.  =  =  1,885.5  Ib. 

o 

Equivalent  evaporation  =  30,227 

Equivalent  evap.  from  and  at  212°  per  Ib.  of  oil  as  fired 


Problem  No.  30.  —  What  is  the  equivalent  evaporation  from  and  at  212°F. 
per  Ib.  of  oil  corrected  for  moisture  in  Problem  23? 

Solution.  —  Wt.  of  oil  corrected  for  moisture  =  14,978.4  Ib. 
Wt.  of  oil  corrected  for  moisture  per  hr.  = 

-  1,872.3  Ib. 


O 

Equiv.  evap.  from  and  at  212°  per  Ib.  of  oil  corrected  for  moisture  = 

30,227 

1^3  =  16.144  Ib. 

Problem  No.  31.  —  What  is  the  efficiency  of  the  boiler  in  Problem  23? 

Solution. 

T,  .,       „.  Ht.  abs.  by  boiler  per  unit  of  time 

Boiler  en.  =  TT.    .  —  5  —  ,  .   .  .     .  —  —  —A  —  -f  —  r 

Ht.  in  fuel  fed  to  furnace  per  unit  of  time 

30,227  X  970.4 
=  1872.3  X  18,752  ~  «*.29  per  cent. 

Problem  No.  32.  —  Assuming  the  steam  was  just  saturated  and  not  super- 
heated in  the  above,  what  would  be  the  factor  of  evaporation  in  Problem  23  ? 

Solution. 

TT  r 

Factor  of  evaporation  =     ^         2  (for  saturated  steam) 

From  Problem  23  PI     =    200.  13  Ib.  per  sq.  in. 

P2   =      14.831b.  per  sq.  in. 
From  Tables  Hi    =1198.1    B.t.u. 

hz    =     136.  96  B.t.u. 

1198.1  -  136.96 
.  '  .  Factor  of  evaporation  —  0704  — 

_   1061.14  '_ 
9704" 

Problem  No.  33.  —  Assuming  the  steam  to  be  97  %  dry,  what  would  be  the 
factor  of  evaporation  in  Problem  23? 

Solution. 
Factor  of  evap.  =  kl  +  *~~  k*  (wet  steam) 


From  Prob.  23,  PI  =  200.  13  Ib.  per  sq.  in. 
P2  =     14.831b.  per  sq.  in. 


ILLUSTRATIVE  PROBLEMS  409 

From  tables       hi   =  heat  of  liquid  at  200.13  Ib.  per  sq.  in. 

=  354 . 9  B.t.u. 
hz   =  heat  of  liquid  of  entering  feed  water 

=  136. 96  B.t.u. 

Li  =  latent  heat  of  evap.  at  200.13  Ib.  per  sq.  in. 
=  843.2  B.t.u. 
X   =  %  dry  steam  =  .97 

354.9  +  0.97  X  843.2  -  136.96 
Factor  of  evap.  =  —  — cmf! — 

=  354.9  +  817.9  -  136.96 

970.4 

_  1035.84  _ 
-"9704"- 

Miscellaneous  Questions  and  Answers  on  Fuel  Oil  and  Steam  Engineering 
1.  How  do  you  compute  proper  size  of  boiler  installation  for  a  power 

plant? 

Answer. — In  order  to  compute  the  proper  size  of  boiler  installation  for  a 

given  power  output,  we  must  know  three  factors: 

(1)  The  Maximum  output  to  be  anticipated. 

(2)  The  Overall  efficiency  of  steam  boilers  and  power  units. 

(3)  The  Maximum  overload  to  be  allowed  on  boilers  in  steam  generation. 
Thus  let  us  assume  that  12,000  kw.  are  desired  at  the  switchboard  of  a 

steam  turbine  installation  and  that  the  overall  efficiency  of  steam  boilers 
steam  turbine  and  electric  generation  is  15%.  What  boiler  capacity  should 
be  installed  if  the  boilers  are  capable  of  carrying  a  50%  overload? 

Since  1  hp.    =  0.746  kw. 
We  proceed  as  follows : 

12000 
Mech.  h.p.  required  at  switchboard  =rp7T« 

Mech.  h.p.  required  to  be  delivered  by  boilers  =pr^r-~  \/  n  i~x. 

U./4O  /\  lj» -L  O 

Since  1  boiler  h.p.  =  13.14  mech.  hp., 

1 2000  1 

Total  boiler  h.p.  required  of  boilers 


0.746  X0.15  ~    13.14 
Since  boilers  are  to  run  at  150%  of  rating,  the  rating  of  boilers  must  be 
12000  11 


0746X015         34       T50 

Questions  Answered  on  Fuel  Oil  Economy 

2.  What  is  the  approximate  increase,  if  any,  in  boiler  repairs  when  coal 
fired  boilers  are  changed  to  oil  ? 

Answer. — The  amount  of  boiler  repairs  is  practically  the  same  when  burn- 
ing oil  as  when  burning  coal,  provided  the  boilers  are  operated  at  the  same 
capacity  and  the  oil  burners  are  properly  adjusted  so  as  not  to  blow  oil  direct 
against  the  boiler  tubes  or  direct  against  the  brick  walls. 

3.  Is  the  back  shot  method  the  best  for  Stirling  boilers? 

Answer. — The  back  shot  oil  burner  is  generally  considered  the  best  for 
Stirling  boilers,  owing  to  the  advantage  gained  by  the  large  combustion 
chamber. 


410  FUEL  OIL  AND  STEAM  ENGINEERING 

4.  Can  you  give  the  comparative  cost  per  1000  pounds  of  steam,  of  coal 
vs.  oil,  including  all  boiler  room  costs?     In  this  question  I  have  in  mind 
modern  firing  facilities.     Give  the  unit  prices  for  both  coal  and  oil. 

Answer. — In  regard  to  the  comparative  costs  of  oil  vs.  coal  the  reader  is 
referred  to  Fig.  145,  page  222  on  which  the  relative  value  of  oil  is  plotted 
against  coal  of  various  qualities.  From  this  diagram  the  reader  can  see  at 
a  glance,  for  instance,  that  oil  costing  $1.50  per  bbl.  is  equivalent  to  coal 
of  10,000  B.t.u.'s  costing  $3.50  per  short  ton  or  coal  of  14,000  B.t.u.'s 
costing  $6.00  per  short  ton. 

5.  What  quantity  of  oil  have  you  found  by  actual  tests  is  necessary  to 
evaporate  the  same  quantity  of  water  as  1  ton  (2240  Ib.)  of  coal,  giving 
B.t.u.'s  in  coal  and  oil? 

Answer. — The  quantity  of  oil  necessary  to  evaporate  the  same  quantity 
of  water  as  one  ton  of  coal  depends  entirely  on  the  heating  value  of  the 
two  fuels  and  the  boiler  efficiency  obtained.  If  the  heating  value  of  coal  is 
14,000  B.t.u.'s  and  the  boiler  efficiency  is  72  %,  each  pound  of  coal  would 
evaporate  10.35  Ib.  of  water  from  and  at  212°.  One  pound  of  oil  containing 
18,000  B.t.u.'s  with  a  boiler  efficiency  of  78%  would  evaporate  14.4  pounds 
of  water  from  and  at  212°.  From  this  you  can  readily  figure  out  that  one 
ton  of  coal  containing  2240  Ib.  would  evaporate  the  same  quantity  of  water 
as  4.8  bbl.  of  oil  each  containing  336  pounds. 

6.  Have  you  found  mechanical  atomizing  to  be  the  most  economical? 
Answer. — Oil  is  atomized  by  steam  in  nearly  all  stationary  boiler  plants 

due  to  the  fact  that  steam  is  more  convenient  than  any  other  method,  and 
the  atomization  is  very  perfect.  As  a  rule  mechanical  atomization  is  not 
used  unless  the  loss  of  fresh  water  used  in  steam  atomization  is  an  important 
consideration. 

7.  What  are  the  relative  merits  of  saturated  and  superheated  steam  for 
atomization?     Mr.  Hawkins  in  his  book,  "The  Economy  Factor  in  Steam 
Power  Plants,"  discounts  the  value  of  superheated  steam.     I  quote  ver- 
batim : 

"On  the  other  hand,  the  action  of  the  superheated  steam  appears  to 
produce  an  unsteady  flame — a  rapid  succession  of  small  puffs  rather  than 
the  steady  uniform  condition  which  is  desired." 

We  are  wondering  if  these  puffs  are  occasioned  by  the  oil  temperature 
being  raised  to  the  flash  point.  We  are  of  the  opinion  that  superheated 
steam  should  prove  more  efficient  than  saturated,  and  to  this  end  are 
arranging  for  test.  Pending  receipt  of  flow  meter  and  calibration  of  our 
orifice,  however,  we  will  appreciate  your  comments. 

Answer. — We  use  superheated  steam  in  preference  to  saturated  steam 
wherever  we  have  super  heaters.  Superheated  steam  atomizes  the  oil  more 
perfectly  than  saturated  steam  and  consequently  it  is  the  general  belief 
that  less  steam  is  required. 

The  quantity  of  steam  required  for  atomizing  can  always  be  reduced  by 
heating  the  oil  to  a  high  temperature  and  it  is,  therefore,  desirable  to  get  the 
oil  as  hot  as  possible  without  heating  it  above  its  flash  point.  We  have 
never  found  the  use  of  superheated  steam  to  cause  an  unsteady  flame  such 
as  is  referred  to  in  Mr.  Hawkins'  book.  We  have  used  steam  having  as  much 
as  160  degrees  of  superheat,  though  normally  we  use  about  100  degrees. 


APPENDIX  II 

HELPFUL   FACTORS   IN   FUEL   OIL   STUDY   AND    CON- 
SERVATION 

The  authors  of  the  work  would  feel  unmindful  of  their  duty  in  setting 
forth  the  elements  of  fuel  oil  and  steam  engineering  did  they  not  at  this 
time  point  out  to  the  reader  some  of  the  helpful  factors  that  are  aiding  in 
fuel  oil  study  and  conservation  in  these  days  of  national  emergency. 

First  and  foremost  must  be  mentioned  the  educative  and  helpful  influence 
of  the  universities  and  technical  colleges  of  the  West — such  as  the  University 
of  California  and  Leland  Stanford  Junior  University.  These  institutions 
are  not  only  prepared  to  train  technical  fuel  oil  specialists,  but  the  eminent 
scientists  and  engineers  upon  their  teaching  staffs  are  contributing  note- 
worthy research  data  for  the  upbuilding  of  efficient  mining  and  utilization 
of  this  important  national  resource.  The  Extension  Division  of  the  Uni- 
versity of  California  is  now  serving  over  three  hundred  thousand  people  in 
the  state  of  California.  Practically  every  conceivable  educative  aid  is 
available  through  this  branch  of  university  instruction.  All  operators  or 
engineers  interested  in  fuel  oil,  its  uses  and  conservation,  may  for  a  small  fee 
enjoy  this  excellent  service.  The  only  other  requirement  on  the  part  of 
the  applicant  is  that  he  be  thoroughly  in  earnest  in  undertaking  such  study. 
To  get  in  touch  with  this  excellent  service,  a  letter  should  be  addressed  to 
Director  of  Extension  Division,  University  of  California,  Berkeley. 

The  California  Railroad  Commission  is  doing  excellent  service  in  the 
efficient  handling  of  the  petroleum  situation.  Authorized  under  the  law  to 
regulate  the  public  utilities  as  to  rates  and  other  matters,  this  commission 
on  its  own  initiative  has  worked  out  a  scheme  of  interconnection  of  power 
companies  in  the  state  of  California  that  will  do  much  in  conserving  the  fuel 
oil  in  that  industry. 

Especial  attention  is  called  to  the  research  investigations  of  the  United 
States  Bureau  of  Mines  and  the  United  States  Bureau  of  Standards.  Much 
of  the  scientific  data  on  fuel  oil  specifications  and  steam  generation  contained 
in  this  work  have  been  gleaned  from  the  various  publications  of  the  Bureau 
of  Mines,  while  the  standardization  of  thermometers  as  treated  in  addition 
to  many  other  aids  in  scientific  precision  described,  must  be  accredited  to 
the  helpful  work  of  the  Bureau  of  Standades.  In  discussions  looking  toward 
the  production  of  petroleum  the  publications  of  the  United  States  Geological 
Survey  are  timely,  as  are  also  the  publications  of  the  California  State 
Mining  Bureau. 

The  Book  on  Steam  of  the  Babcock  &  Wilcox  Company  is  perhaps  the 
most  helpful  of  its  kind  in  existence  in  setting  forth  the  elementary  laws  of 
steam  engineering  in  a  practical  manner,  and  the  authors  are  greatly  in- 
debted to  it  for  many  helpful  items  in  the  present  work. 

411 


412 


FUEL  OIL  AND  STEAM  ENGINEERING 


o-S 


HELPFUL  FACTORS  IN  FUEL  OIL  STUDY 


413 


414  FUEL  OIL  AND  STEAM  ENGINEERING 

In  regard  to  current  aids  in  the  technical  press,  the  only  paper  in  existence 
that  devotes  a  regular  department  to  the  technical  discussion  of  fuel  oil  and 
steam  engineering  is  the  Journal  of  Electricity  published  in  San  Francisco. 
This  journal  is  now  in  its  thirty-third  year  of  publication  and  is  the  recog- 
nized authority  on  this  line  of  discussion.  Electrical  World  and  POWER 
published  in  New  York  City  also  publish  much  timely  and  helpful  data 
along  the  line  of  fuel  oil  and  steam  engineering. 

The  work  of  the  Pacific  Coast  Section,  N.E.L.A.  along  lines  of  fuel  oil 
economy  in  steam  power  generation  has  proven  most  helpful.  Through  this 
means  of  expression  the  great  power  companies  of  the  West  which  use  oil 
as  a  fuel  are  contributing  noteworthy  aids  to  efficient  uses  of  this  product. 

The  American  Society  of  Mechanical  Engineers  and  the  American  In- 
stitute of  Electrical  Engineers  constitute  the  two  great  national  societies 
of  professional  status  that  are  exceedingly  helpful  in  fuel  oil  study. 


APPENDIX  III 

RULES  AND  REQUIREMENTS  OF  THE  NATIONAL  BOARD 
OF  FIRE  UNDERWRITERS  FOR  THE  STORAGE  AND  USE 
OF  FUEL  OIL  AND  FOR  THE  CONSTRUCTION  AND  IN- 
STALLATION OF  OIL  BURNING  EQUIPMENTS 

CLASS  A 

LARGE  SUPPLY  OR  STORAGE  TANKS  FOR  OILS  HAVING  A  FLASH  POINT 

ABOVE  150°F. 

(Abel-Pensky  Flash  Point  Test) 

This  flash  point  corresponds  closely  to  160°Fahr.  (Tagliabue  Open  Cup 
Tester)  which  may  be  used  for  rough  estimations  of  the  flash  points.  These 
storage  tanks  are  generally  used  for  storage  hi  oil  fields,  oil  refineries  or 
distributing  stations  and  are  in  most  cases  installed  above  ground.  The 
hazards  of  such  systems  of  storage  depend  upon  the  distance  from  burnable 
property  and  upon  the  topography  of  the  surrounding  land. 

TABLE  1 


Minimum  distance  of  tanks 

Capacity  in  gallons 

To  line  of  adjoining 

To  any  other  tank, 

property  which  may 

feet 

be  built  upon,  feet 

1,000 

10 

2 

2,000 

20 

2 

16,000 

25 

2 

24,000 

30 

2 

36,000 

40 

3 

48,000 

50 

3 

60,000 

60 

3 

96,000 

75 

3 

150,000 

85 

3 

200,000 

100 

15 

300,000 

150 

25 

500,000 

250 

35 

1,000,000 

300 

50 

2,000,000 

350 

75 

Unlimited 

400 

200 

415 


416  FUEL  OIL  AND  STEAM  ENGINEERING 

1.  Capacity  and  Location  of  Tanks. 

(a)  Tanks  to  be  so  located  as  to  avoid  undue  exposure  of  adjacent  burnable 
property.  The  distances  specified  in  Table  No.  1  are  for  plants  or  storage 
tanks  located  outside  of  fire  limits. 

(6)  Tanks  to  be  located  at  lowest  point  available  and  so  placed  as  to  avoid 
possible  danger  from  high  water.  When  near  a  stream  without  tide,  tanks 
to  be  located  down-stream  from  the  water  front  of  any  adjacent  town.  On 
tide  water  tanks  to  be  located  well  away  from  shipping  districts. 

(c)  When  it  is  impossible  to  locate  tanks  as  specified  in  Rule  Ib,  each  tank 
to  be  surrounded  with  an  embankment  or  dike  not  less  than  4  feet  in  height 
and  having  a  capacity  not  less  than  fifty  per  cent,  greater  than  the  tank  to 
be  protected. 

(d)  Embankments  or  dikes  to  be  made  of  earth,  reinforced  concrete  or 
brick.     If  made  of  earth,  embankments  to  be  firmly  and  completely  built  of 
earth  from  which  stones,  vegetable  matter,  etc.,  have  been  removed,  and 
to  have  a  crown  of  not  less  than  three  feet  and  a  slope  of  at  least  2  to  1  on 
both  sides.      If  made  of  reinforced  concrete  or  brick  to  be  designed  to  provide 
protection  equivalent  to  an  earth  embankment  with  a  sufficient  factor  of 
safety  to  allow  for  the  effect  of  fire  on  the  concrete  or  brick  facing. 

(e)  Embankments  or  dikes  to  be  continuous,  with  no  openings  for  piping 
or  roadways.     Piping  to  be  laid  well  below  the  foundation  of  the  embank- 
ments and,  at  points  where  it  is  necessary  to  pass  over  the  embankment, 
properly  built  steps  or  concrete  roadway  to  be  provided. 

2.  Height  of  Tanks. 

Vertical  tanks  must  not  exceed  30  feet  in  height. 

3.  Material  and  Construction  of  Tanks. 

(a)  Tanks  must  be  constructed  of  iron  or  steel  plates  of  a  gauge  depending 
upon  the  capacity  as  specified  in  the  following  table. 

TABLE  2 — THICKNESS  OF  METAL  FOR  ABOVE  GROUND  TANKS. 
HORIZONTAL 


Maximum  diameter 

Minimum  thickness 

Heads,  in. 

Shell,  in. 

Not  over 
5  feet  to 
8  feet  to 

5  feet 

KG 

y* 

% 

%4 
^6 

M 

8  feet 

11  feet              

VERTICAL 

Capacity  5,000  gallons  or  less,  diameter  less  than  40  feet. 
Bottom          No.    8  U.  S.  gauge. 
Bottom  ring  No.    8  U.  S.  gauge. 
Other  rings    No.  10  U.  S.  gauge. 
Top  No.  12  U.  S.  gauge. 


RULES  AND  REQUIREMENTS 


417 


Capacity  10,000  gallons  or  less,  diameter  less  than  40  feet. 
Bottom  No.    8  U.  S.  gauge. 

Bottom  ring  No.  7  U.  S.  gauge. 
Other  rings  No.  8  U.  S.  gauge. 
Top  No.  12  U.  S.  gauge. 

Other  vertical  tanks  to  be  of  material  having  a  thickness  of  not  less  than 
indicated  in  the  following.  Figures  in  all  columns  excepting  the  first  refer 
to  U.  S.  Standard  Gauge. 


2d 

3d 

4th 

5th 

6th 

Diameter  in 
feet 

Top 

Top 
ring 

ring 
from 

ring 
from 

ring 
from 

ring 
from 

ring 
from 

Bot- 
tom 

top 

top 

top 

top 

top 

80 

10 

7 

7 

3 

0 

3-0 

5-0 

10 

75 

10 

7 

7 

4 

1 

2-0 

4-0 

10 

70 

10 

7 

7 

4 

1 

2-0 

4-0 

10 

65 

10 

7 

7 

5 

1 

0 

3-0 

10 

60 

10 

7 

7 

5 

2 

0 

2-0 

10 

55 

10 

7 

7 

6 

3 

1 

2-0 

10 

50 

10 

7 

7 

7 

4 

1 

0 

10 

45 

10 

7 

7 

7 

5 

3 

1 

10 

40  &  less 

10 

7 

7 

7 

5 

3 

2 

10 

All  riveted  joints  to  have  an  efficiency  of  at  least  60  per  cent. 

Tanks  of  greater  capacity  than  given  above  shall  be  of  material  of  sufficient 
thickness  to  safely  hold  the  contents  and  proportionately  heavier. 

NOTE. — For  materials  to  be  used  in  smaller  tanks  refer  to  Table  No.  4 
giving  weights  of  material  for  underground  storage  tanks. 

(b)  All  joints  of  tanks  must  be  riveted  and  soldered,  riveted  and  caulked, 
brazed  or  welded,  or  made  by  some  equally  satisfactory  process.  Tanks 
must  be  tight  and  sufficiently  strong  to  bear  without  injury  the  most  severe 
strains  to  which  they  are  liable  to  be  subjected  in  transportation  or  use. 
Tanks  shipped  complete  must  be  suitably  reinforced  to  prevent  injury  to  the 
joints. 

,(c)  Tanks  must  be  provided  with  a  vent  pipe  terminating  in  a  weather- 
proof hood  containing  a  non-corrodible  screen.  In  case  the  vent  pipe  is  not 
permanently  open  a  suitable  safety  relief  must  be  provided.  When,  in 
order  to  provide  a  means  for  relieving  pressure,  manhole  covers  are  not 
provided  with  bolts  or  clamps,  the  openings  must  be  protected  by  a  non- 
corrodible  wire  mesh  screen  (not  less  than  20  X  20  meshes  per  square  inch) 
which  may  be  removable  but  must  be  normally  securely  held  in  place. 

(d)  Outside  surfaces  of  tanks  must  be  thoroughly  protected  against  corro- 
sion by  a  suitable  rust-resisting  paint. 

4.  Support  for  Tanks. 

Tanks  to  be  set  upon  a  substantial  foundation,  and  when  elevated  above 
the  ground  level,  supports  are  to  be  of  non-combustible  material,  with 
27 


418  FUEL  OIL  AND  STEAM  ENGINEERING 

exception  of  suitable  wooden   cushions.     All  above-ground  tanks  to  be 
thoroughly  grounded  electrically. 

5.  Means  for  Extinguishing  Fires  in  Tanks. 

(a)  Each  tank  to  be  equipped  with  an  independent  steam  pipe  for  use  in 
case  of  fire,  the  outlet  of  which  is  to  be  inside  the  tank,  above  the  surface 
of  the  oil. 

This  pipe  to  be  of  ample  capacity,  but  never  smaller  than  ^  inch. 

(b)  Steam  which  is  to  be  supplied  from  conveniently  located  boilers  to  be 
controlled  by  valves  outside  the  embankments  surrounding  the  tanks. 

NOTE. — Systems  providing  protection  equivalent  to  the  above  may  be 
used.  Such  systems  generally  embody  the  use  of  blanketing  gas,  and  when 
the  source  of  supply  is  thoroughly  reliable,  may  be  satisfactorily  employed 
where  a  supply  of  steam  is  not  available. 

6.  Pumps. 

Pumps  used  in  connection  with  the  supply  and  discharge  of  the  tank  shall 
be  located  outside  of  the  reservoir  walls  and  at  such  a  point  that  they 
will  be  accessible  at  all  times,  even  if  the  oil  in  the  tank  or  reservoir  should 
be  on  fire. 

7.  Pipe  Connections. 

All  oil  conveying  pipes  to  be  laid  underground,  but  under  no  circumstances 
shall  they  break  through  the  reservoir  walls. 

The  above  rule  does  not  apply  to  pipes  passing  under  the  reservoir  wall 
and  laid  well  below  the  surface  of  the  ground. 

8.  Controlling  Valves. 

(a)  There  shall  be  a  gate  valve  located  at  the  tank  in  each  oil  conveying 
pipe.  In  case  two  or  more  tanks  are  cross-connected  there  shall  be 
a  gate  valve  at  each  tank  in  each  cross-connection. 

(ft)  There  shall  be  a  gate  valve  in  the  discharge  and  suction  pipes  near  the 
pump  and  a  check  valve  in  the  discharge  pipe,  located  underground. 

9.  Indicator. 

There  shall  be  a  reliable  indicator  to  show  the  level  of  the  oil  in  the  tank. 
Indicator  to  be  of  such  a  form  that  its  derangement  will  not  permit  escape 
of  oil. 

10.  Plans  and  Specifications. 

A  complete  set  of  plans  and  specifications  of  proposed  installation  shall  be 
submitted  to  the  Inspection  Department  having  jurisdiction  before  beginning 
construction. 

CLASS  B 

INDIVIDUAL    OIL-BURNING    EQUIPMENTS   FOR    OTHER    THAN    HOUSEHOLD 

PURPOSES 

Apparatus  using  oil  for  fuel,  however  safe -guarded,  introduces  a  distinct 
increase  in  hazard  which  should  be  recognized. 

Where  used,  the  following  rules  should  be  rigidly  observed. 

All  oil  used  for  fuel  purposes  under  these  rules  shall  show  a  flash  test  of 
not  less  than  150°F.  (Abel-Pensky  Flash  Point  Tester.)  This  flash  point 


RULES  AND  REQUIREMENTS 


419 


corresponds  closely  to  160°F.  (Tagliabue  Open  Cup  Tester),  which  may  be 
used  for  rough  estimations  of  the  flash  point. 


FIG.  246. — A  diagrammatic  sketch  of  an  oil  tank  shown  below  the  basement 
floor  level  when  boiler  is  located  in  a  basement  where  the  sidewalk  is  not  ex- 
cavated. 

11.  Capacity  and  Location  of  Tanks. 

(a)  In  closely  built  up  districts  or  within  fire  limits  tanks  to  be  located 
underground  with  tops  of  tanks  not  less  than  three  feet  below  the  surface  of 


FIG.  247. — Here  is  shown  an  oil  tank  located  4  feet  below  the  boiler-room 
floor  in  which  the  boiler  is  in  the  basement  and  the  sidewalk  has  been  excavated. 
This  construction  is  agreeable  to  the  rule  of  the  Board  of  Fire  Underwriters. 

the  ground  and  below  the  level  of  the  lowest  pipe  in  the  building  to  be  sup- 
plied.    Tanks  may  be  permitted  underneath  a  building  if  buried  at  least 


420 


FUEL  OIL  AND  STEAM  ENGINEERING 


three  feet  below  the  basement  floor  which  is  to  be  of  concrete  not  less  than 
6  inches  thick.  Tanks  shall  be  set  on  a,  firm  foundation  and  surrounded  with 
soft  earth  or  sand,  well  tamped  into  place.  No  air  space  shall  be  allowed 
immediately  outside  of  tanks.  Tank  may  have  a-  test  well,  provided  test 
well  extends  to  near  bottom  of  tank,  and  top  end  shall  be  hermetically  sealed 
and  locked  except  when  necessarily  open.  When  tank  is  located  under- 
neath a  building  the  test  well  shall  extend  at  least  12  feet  above  source  of 
supply.  The  limit  of  storage  permitted  shall  depend  upon  the  location  of 
tanks  with  respect  to  the  building  to  be  supplied  and  adjacent  buildings,  as 
given  in  the  following  table. 


FIG.  248. — The  view  shows  an  oil  tank  below  the  level  of  the  boiler  room  floor 
where  the  sidewalk  has  been  excavated.  The  installation  is  agreeable  to  the 
Board  of  Fire  Underwriters'  specifications. 

TABLE  3. — PERMISSIBLE    AGGREGATE    CAPACITY    IF    LOWER    THAN    ANY 
FLOOR,  BASEMENT,   CELLAR  OR  PIT  IN  ANY  BUILDING  WITHIN  RADIUS 

SPECIFIED 

Capacity  Radius,  feet 

Unlimited 50 

20,000  gallons 30 

5,000  gallons 20 

1,500  gallons 10 

*500  gallons Less  than  10 

*  In  this  case  tank  to  be  entirely  encased  in  6  inches  of  concrete. 

(6)  When  located  underneath  a  building  no  tank  to  exceed  a  capacity  of 
9,000  gallons  and  basement  floors  to  be  provided  with  ample  means  of  sup- 
port independent  of  any  tank  or  concrete  casing. 

(c)  Outside  of  closely  built  up  districts  or  outside  of  fire  limits,  above- 
ground  storage  tanks  may  be  permitted  as  specified  in  Rule  1,  provided 


RULES  AND  REQUIREMENTS  421 

drainage  away  from  burnable  property  in  case  of  breakage  of  tanks  is 
arranged  for  or  suitable  dikes  built  around  the  tanks.  When  dikes  are 
employed  the  distances  specified  in  Table  1  are  to  be  taken  as  distances  to 
nearest  points  of  dikes. 

When  above-ground  tanks  are  used  all  piping  must  be  arranged  so  that  in 
case  of  breakage  of  piping  the  oil  will  not  be  drained  from  tanks.  This 
requirement  prohibits  the  use  of  gravity  feed  from  storage  tanks.  Above- 
ground  tanks  of  less  than  1,000  gallons  capacity  without  dikes  may  be 
permitted  in  case  suitable  housings  for  the  protection  of  the  tanks  against 
njury  are  provided. 

12.  Material  and  Construction  of  Tanks. 

(a)  Tanks  must  be  constructed  of  iron  or  steel  plate  of  a  gauge  depending 
upon  the  capacity  as  specified  in  the  following  tables : 

TABLE  4. — UNDERGROUND  TANKS  INSIDE  OF  SPECIFIED  FIRE  LIMITS,  OR 
WITHIN  TEN  FEET  OF  A  BUILDING  WHEN  OUTSIDE  SUCH  LIMITS 

Capacity,  gallons  Minimum  thickness 

of  material 

1  to       560 14  U.  S.  gauge 

561  to    1,100 12  U.  S.  gauge 

1,101  to    4,000 7  U.  S.  gauge 

4,001  to  10,500 y±" 

10,501  to  20,000 y^" 

20,001  to  30,000 %" 


TABLE   5. — UNDERGROUND   TANKS   OUTSIDE   OF   SPECIFIED    FIRE  LIMITS, 
PROVIDED  THE  TANKS  ARE  TEN  FEET  OR  MORE  FROM  A  BUILDING 

Capacity,  gallons  Minimum  thickness 

of  material 

1  to         30 18  U.  S.  gauge 

31  to       350 16  U.  S.  gauge 

351  to    1,100 14  U.  S.  gauge 

1,101  to    4,000 7  U.  S.  gauge 

4,001  to  10,500 Y±" 

10,501  to  20,000 %" 

20,001  to  30,000 %" 


Tanks  of  greater  capacity  than  30,000  gallons  must  be  made  of  proportion- 
ately heavier  metal. 

(6)  All  joints  of  tanks  must  be  riveted  and  soldered,  riveted  and  caulked, 
welded  or  brazed  together,  or  made  by  some  equally  satisfactory  process. 
To  be  tight  and  sufficiently  strong,  to  bear  without  injury  the  most  severe 
strains  to  which  they  are  liable  to  be  subjected  in  practice.  The  shells  of 
tanks  to  be  properly  reinforced  where  connections  are  made  and  all  connec- 


422  FUEL  OIL  AND  STEAM  ENGINEERING 

tions  should  as  far  as  practicable  be  made  through  the  upper  side  of  tanks 
above  oil  level. 

(c)  Tanks  shall  be  thoroughly  coated  on  the  outside  with  tar,  asphaltum 
or  other  suitable  rust-resisting  material. 

NOTE. — The  protection  required  for  tanks  will  depend  upon  the  condition 
of  the  soil  in  which  they  are  installed.  When  the  soil  is  impregnated  with 
corrosive  materials  tanks  should  be  made  of  heavier  metal  in  addition  to 
being  protected  as  specified  above. 

13.  Fill  and  Vent  Pipes. 

(a)  Each  underground  storage  tank  having  a  capacity  of  over  1,000  gallons 
to  be  provided  with  at  least  a  1  inch  vent  pipe  extending  from  the  top  of  the 
tank  to  a  point  outside  of  building.  Vent  pipe  to  terminate  at  a  point  at 
least  12  feet  above  the  level  of  the  top  of  the  highest  tank  car  or  other  reser- 
voir from  which  the  storage  tank  may  be  filled.  Terminal  to  be  provided 
with  a  hood  or  goose  neck  protected  by  a  non-corrodible  screen  and  to  be 
located  remote  from  fire  escapes  and  never  nearer  than  3  feet,  measured 
horizontally  and  vertically,  from  any  window  or  other  opening.  Vent  pipes 
from  two  or  more  tanks  may  be  connected  to  one  upright,  provided  the 
connection  is  made  at  a  point  at  least  one  foot  above  level  of  source  of  supply. 
"  (6)  Tanks  having  a  capacity  of  less  than  1,000  gallons  may  be  provided 
with  combined  fill  and  vent  pipes  so  arranged  that  the  fill  pipe  cannot  be 
opened  without  opening  the  vent  pipe,  these  pipes  to  terminate  in  a  metal 
box  or  casting  provided  with  a  lock. 

(c)  Fill  pipes  for  tanks  which  are  installed  with  permanently  open  vent 
pipes  must  be  provided  with  metal  covers  or  boxes  which  are  to  be  kept 
locked  except  during  filling  operations. 

(d)  Fill  and  vent  pipes  for  tanks  located  under  buildings  are  to  be  run 
underneath  the  concrete  floor  to  outside  of  building. 

14.  Indicator. 

Some  device  for  indicating  the  level  of  the  oil  is  desirable.  Where  used, 
such  attachment  shall  be  connected  through  substantial  fittings  so  as  to 
minimize  exposure  of  the  oil,  and  devices  the  breakage  of  which  will  allow 
the  escape  of  oil,  must  not  be  used. 

15.  Filters. 

Suitable  filters  or  strainers  for  the  oil  should  be  installed  and  preferably 
be  located  in  supply  line  before  reaching  pump.  Filter  to  be  arranged  so  as 
to  be  readily  accessible  for  cleaning. 

16.  Feed  Pumps. 

(a)  Must  be  of  approved  design,  secure  against  leaks. 

NOTE. — Stuffing  box,  if  used,  should  be  provided  with  a  removable 
cupped  gland  designed  to  compress  the  packing  against  the  shaft  and  ar- 
ranged so  as  to  facilitate  removal.  Packing  affected  by  the  oil  must  not 
be  used. 

(6)  To  be  arranged  so  that  dangerous  pressures  will  not  be  obtained  in  any 
part  of  system,  and  it  is  further  recommended  that  feed  pumps  be  inter- 
connected with  pressure  air  supply  to  burners  in  order  to  prevent  flooding. 


RULES  AND  REQUIREMENTS  423 

17.  Gauge  Glasses  and  Pet  Cocks. 

Glass  gauges,  the  breakage  of  which  would  allow  the  escape  of  oil,  are  to  be 
avoided.  If  their  use  is  necessary,  they  should  have  substantial  protection 
or  be  arranged  so  that  oil  will  not  escape  if  broken.  Pet  cocks  must  not  be 
used  on  oil  carrying  parts  of  system. 

18.  Receivers  or  Accumulators. 

(a)  If  used,  they  must  be  designed  so  as  to  secure  a  factor  of  safety  of  not 
less  than  6.  Must  be  subjected  to  a  pressure  test  of  not  less  than  twice  the 
working  pressure. 

(6)  The  capacity  of  the  oil  chamber  must  not  exceed  10  gallons. 

(c)  To  be  equipped  with  pressure  gauge. 

(d)  To  be  provided  with  an  automatic  relief  valve  set  to  operate  at  a  safe 
pressure  and  connected  by  an  overflow  pipe  to  supply  tank,  and  so  arranged 
that  the  oil  will  automatically  drain  back  to  the  supply  tank  immediately 
on  closing  down  the  pump. 

19.  Standpipes. 

(a)  If  used,  their  capacity  shall  not  exceed  10  gallons. 

(&)  To  be  of  substantial  construction,  equipped  with  an  overflow,  and  so 
arranged  that  the  oil  will  automatically  drain  back  to  the  supply  tank  on 
shutting  down  pump,  leaving  not  over  one  gallon,  where  necessary,  for  prim- 
ing, etc. 

(c)  If  vented,  the  opening  should  be  at  the  top  and  may  be  connected  with 
the  outside  vent  pipe  from  storage  tank,  above  level  of  source  of  supply. 

20.  Piping. 

(a)  Standard  full  weight  wrought  iron,  steel  or  brass  pipe  with  substantial 
fittings  to  be  used  and  to  be  carefully  protected  against  injury.  Piping 
under  pressure  must  be  designed  to  secure  a  factor  of  safety  of  not  less  than 
6,  and  after  installation  to  be  tested  to  a  pressure  not  less  than  twice  the 
working  pressure. 

(6)  Piping  to  be  run  as  directly  as  possible,  and  laid  so  that  the  pipes  are 
pitched  toward  the  supply  tanks  without  traps. 

(c)  Overflow  and  return  pipes  to  be  at  least  one  size  larger  than  the  supply 
pipes,  and  no  pipe  to  be  less  than  one-half  inch  pipe  size. 

(d)  All  connections  to  be  perfectly  tight  with  well-fitted  joints.     Unions, 
if  used,  to  be  of  approved  type  having  at  least  one  face  of  the  joint  made  of 
brass  and  having  conically  faced  seats,  obviating  the  use  of  packing  or 
gaskets. 

(e)  Pipes  leading  to  the  surface  of  the  ground  to  be  cased  or  jacketed 
where  necessary  to  prevent  loosening  or  breakage,  and  proper  allowance 
should  be  made  for  expansion  and  contraction,  jarring  and  vibration. 

(/)  Connection  to  outside  tanks  to  be  laid  below  the  frost  line  and  not  to 
be  located  near  nor  placed  in  same  trench  with  other  piping. 

(g)  Openings  for  pipes  through  outside  walls  to  be  securely  cemented  and 
made  oil  tight. 

21.  Valves,  etc. 

(a)  Readily  accessible  shut-off  valves  to  be  provided  in  the  supply  line 
as  near  to  the  tank  as  practicable,  and  additional  shut-offs  to  be  installed  in 
the  main  line  inside  building  and  at  each  oil  consuming  device. 


424  FUEL  OIL  AND  STEAM  ENGINEERING 

(6)  Controlling  valves  in  which  oil  under  pressure  is  in  contact  with  the 
stem  to  be  provided  with  stuffing  box  of  liberal  size,  containing  a  removable 
cupped  gland  designed  to  compress  the  packing  against  the  valve  stem  and 
arranged  so  as  to  facilitate  removal.  Packing  affected  by  the  oil  mu&t  not 
be  used. 

(c)  The  use  of  approved  automatic  shut-offs  for  the  oil  supply  in  case  of 
breakage  of  pipes  or  excessive  leakage  in  building  is  recommended. 

CLASS  C 

OIL  CONVEYOR  OB  CARRIERS 

22.  Steamers,  etc. 

(a)  Steamers,  barges  or  vessels  loading  or  discharging  oil  in  bulk,  shall  not 
load  or  discharge  at  wharves  other  than  those  used  by  the  oil  company, 
and  such  wharves  shall  be  well  isolated  from  all  burnable  property  or 
wharfage. 

(6)  There  shall  be  a  gate  valve  immediately  at  the  point  in  the  pipe  line 
where  connection  is  made  with  the  hose  leading  to  the  ship  for  the  purpose 
of  shutting  off  the  oil,  and  there  shall  be  another  gate  valve  in  this  line  of 
pipe  at  a  distance  of  at  least  10  feet  back  from  the  wharf,  where  it  will  be 
readily  accessible  for  the  purpose  of  shutting  the  oil  off  in  event  of  failure  on 
the  part  of  the  valve  first  mentioned. 

(c)  A  tight  connection  shall  be  made  with  the  hose  length  at  the  wharf 
by  means  of  a  carefully  threaded  coupling,  to  prevent  leakage  and  accumula- 
tion of  oil  around  the  piers. 

(d)  Lights.     No  fire  nor  open  lights  to  be  allowed  on  the  vessel  while  at  the 
wharf. 

CLASS  D 

APPARATUS  FOR  COOKING  AND  HEATING  FOR  HOUSEHOLD  USE 

The  use  of  oil  as  fuel  for  domestic  purposes  is  regarded  from  the  insurance 
viewpoint  as  more  hazardous  than  the  use  of  ordinary  fuel,  such  as  coal, 
wood  and  coke. 

Where  these  systems  are  used  their  hazards  should  be  recognized  and 
the  following  rules  and  precautions  should  be  observed.  All  oil  used  for 
fuel  under  these  rules  shall  show  a  flash  test  of  not  less  than  150°F.  (Abel- 
Pensky  Flash  Point  Tester.)  This  flash  point  corresponds  closely  to 
160°F.  (Tagliabue  Open  Cup  Tester),  which  may  be  used  for  rough  esti- 
mations of  the  flash  point. 

23.  Capacity  and  Location  of  Storage  Tanks.     (See  Rule  11.) 

24.  Material  and  Construction  of  Tanks.     (See  Rule  12.) 
26.  Fill  and  Vent  Pipes.     (See  Rule  13.) 

26.  Pump. 

Oil  pump  used  in  filling  auxiliary  tank  from  the  main  supply  tank  to  be 
approved  type,  "secure  against  leaks,  with  check  valves  located  as  close  to 
the  pump  as  convenient.  Pumps  should  be  rigidly  fastened  in  place. 

NOTE. — Stuffing  box,  if  used,  should  be  provided  with  a  removable 
cupped  gland  designed  to  compress  the  packing  against  the  shaft  and 


RULES  AND  REQUIREMENTS  425 

arranged  so  as  to  facilitate  removal.     Packing  affected  by  the  oil  must  not 
be  used. 

27.  Auxiliary  Supply  Tank. 

(a)  If  used,  shall  not  exceed  five  gallons  in  capacity,  except  by  special 
consent  of  the  Inspection  Department  having  jurisdiction. 

(6)  Shall  be  located  at  least  10  feet,  measured  horizontally,  from  the 
burners. 

(c)  Shall  be  provided  with  an  overflow  connection  draining  to  the  supply 
tank  and  a  vent  pipe  leading  outside  the  building,  the  latter  to  have  a 
weatherproof  hood.  To  be  constructed  of  brass,  copper  or  galvanized 
plate  not  less  than  0.050"  (No.  18  U.  S.  standard  gauge)  in  thickness.  Joints 
to  be  made  as  specified  for  outside  storage  tanks. 

28.  Piping. 

(a)  Standard,  full  weight,  wrought  iron,  steel  or  brass  pipe  with  substantial 
fittings  to  be  used  and  to  be  carefully  protected  against  injury. 

(6)  Supply  pipe  to  be  not  less  than  one-fourth  inch  sizes,  and  overflow 
and  return  pipes  to  be  at  least  one  size  larger. 

(c)  Pipe  connections  to  tanks  to  be  suitably  reinforced  and  proper  allow- 
ance to  be  made  for  expansion  and  contraction^  jarring  and  vibration. 

(d)  Openings  for  pipes  through  outside  walls  to  be  securely  cemented  and 
made  oil  tight. 

(e)  All    connections    to   made   perfectly   tight   with  well  fitted   joints. 
Unions,  if  used,  to  be  of  approved  type,  having  at  least  one  face  of  the  joint 
made  of  brass  and  having  a  conically  faced  joint,  obviating  the  use  of  packing 
or  gaskets. 

(/)  Piping  to  be  run  as  directly  as  possible,  and  to  be  laid  so  that  the  pipes 
are  pitched  back  to  the  storage  tank  without  traps. 

29.  Valves. 

(a)  Readily  accessible  valves  to  be  provided  near  each  burner  and  also 
close  to  the  auxiliary  tank  in  the  pipe  leading  to  burners. 

(6)  Controlling  valves  to  be  constructed  as  specified  in  Rule  21-b. 

30.  Installation  of  Burners. 

(a)  Overflow. — Burners  shall  be  installed  with  oerflow  attachment  so 
arranged  that  any  surplus  oil  will  drain  by  gravity  from  the  burner  through 
a  pipe  into  a  substantially  constructed  reservoir  having  a  capacity  of  not  less 
than  that  of  the  auxiliary  tank. 

Each  tank  to  be  constructed  and  vented  as  provided  for  auxiliary  tanks. 
(See  Rule  27.) 

(6)  Draughts. — No  dampers  to  be  used  in  smoke  pipe  between  burner  and 
chimney.  Any  regulation  of  draught  which  is  necessary  is  to  be  accom- 
plished through  the  dampers  in  front. 

31.  Construction  of  Burners. 

(a)  The  size  of  the  orifice  through  which  the  oil  is  supplied  to  the  burners 
should  be  limited  to  furnish  only  sufficient  oil  for  the  maximum  burning 
conditions  when  the  controlling  valves  are  wide  open. 

(6)  Valves  to  be  arranged  so  as  not  to  enlarge  the  orifice. 


426  FUEL  OIL  AND  STEAM  ENGINEERING 

(c)  Burners  containing  chambers  which  allow  the  dangerous  accumulation 
of  gases  are  prohibited. 

(d)  Burners  containing  oil  conveying  pipes  or  parts  subject  to  intense  heat 
or  subject  to  stoppage  from  carbonization  are  prohibited. 

(e)  Burners  should  be  designed  so  that  they  can  be  easily  cleaned,  and 
so  as  not  to  allow  leakage  of  oil. 

32.  Instruction  Card. 

A  card  giving  complete  instructions  in  regard  to  the  care  and  operation 
of  the  system  to  be  permanently  placed  near  the  apparatus. 


RULES  GOVERNING  CONSTRUCTION  AND  INSTALLATION 

OF  OIL  BURNING  EQUIPMENT  AND  STORAGE 

AND  USE  OF  FUEL  OILS  ADOPTED  BY  THE 

BOARD  OF  STANDARDS  AND  APPEALS 

CITY  OF  NEW  YORK 

FUEL  OIL  RULES 

Rule  1.  Definition.  Flash  Point  and  Specific  Gravity. — The  term  "oil 
used  for  fuel  purposes"  under  these  rules  includes  any  liquid  or  mobile 
mixture,  substance  or  compound  derived  from  or  including  petroleum. 

All  oil  used  for  fuel  purposes  under  these  rules  shall  show  a  minimum  flash 
point  of  not  less  than  one  hundred  and  seventy-five  (175)  degrees  Fahren- 
heit, in  an  open  cup  tester,  or  if  closed  cup  tester  be  used  a  minimum  of  not 
less  than  one  hundred  and  fifty  (150)  degrees  Fahrenheit,  and  its  specific 
gravity  shall  be  not  less  than  0.933  (20°B.)  at  a  temperature  of  sixty  (60) 
degrees  Fahrenheit;  and  must  not  be  fed  from  the  tank  to  the  suction  pump 
at  a  pre-heat  temperature  higher  than  its  flash  point. 

Rule  2.  Manner  of  Storage. — Oil  to  be  used  as  fuel  for  commercial, 
heating  and  power  purposes  on  the  premises  where  stored  shall  be  at  all 
times  contained  in  metal  tanks  with  all  openings  or  connections  through  the 
tops  of  the  tanks,  except  a  clean-out  plug  in  the  bottom ;  and,  when  located 
inside  of  a  building,  must  at  all  times  be  placed  in  the  cellar  or  lowest  story 
of  such  building,  and  at  least  two  (2)  feet  in  a  horizontal  direction  from  any 
supporting  portion  of  the  structure,  and  if  practicable  shall  be  buried  under- 
neath the  lowest  floor  or  ground. 

Rule  3.  Location  of  Tanks.  Existing  Buildings. — No  storage  of  fuel  oil 
shall  be  permitted  in  a  building  of  frame  construction  within  the' fire  limits, 
or  in  buildings  of  hazardous  occupancy  as  so  defined  by  the  fire  commissioner. 

If  placed  in  buildings  already  erected,  if  not  buried  beneath  the  lowest 
floor  or  ground,  such  tanks  shall  be  placed  in  an  enlosure  the  floor  of  which 
shall  be  at  least  three  (3)  feet  below  the  surface  of  the  cellar  or  lower  story; 
or  if  by  reason  of  water  or  foundation  conditions,  or  if  on  rock  bottom,  the 
tank  may  be  placed  above  the  surface  of  the  ground,  but  in  any  case  subject 
to  the  conditions  as  hereinafter  described  under  Rule  5. 

Rule  4.  Location  of  Tanks — New  Buildings. — In  buildings  hereafter 
erected  the  bottom  of  the  fuel  oil  service  tanks  shall  be  located  in,  or  below 


RULES  AND  REQUIREMENTS  427 

the  floor  level  of  the  cellar  or  lowest  story  as  shall  be  determined  by  the 
Superintendent  of  Buildings  under  the  provisions  of  Rule  2. 

Rule  5.  Enclosure  of  Tanks. — In  either  existing  or  new  buildings  such 
fuel  oil  service  tanks  shall  be  enclosed  in  an  unpierced  wall  and  floor  of 
approved  masonry  or  reinforced  concrete,  made  oilproof  and  waterproof,  and 
not  less  than  twelve  (12)  inches  in  thickness;  and  also  of  sufficient  thickness 
to  properly  support  any  lateral  pressure,  and  to  be  of  lateral  dimensions 
at  least  one  (1)  foot  greater  on  all  sides  than  the  outside  dimensions  of  the 
tank.  These  walls  are  to  be  carried  up  to  a  height  of  at  least  one  (1)  foot 
above  the  tank,  or  the  supply  and  feed  connections  thereto,  and  roofed 
over  with  reinforced  concrete  or  its  equivalent  at  least  twelve  (12)  inches 
thick  and  capable  of  sustaining  a  live  load  of  at  least  three  hundred  (300) 
pounds  per  square  foot;  and  if  not  buried  below  the  ground,  placed  so  as  to 
leave  a  clear  and  open  space  (except  for  pipe  connections)  of  at  least  two 
(2)  feet  between  such  roof  over  the  enclosure  and  the  underside  of  the 
ceiling  above.  The  roof  of  every  enclosure  shall  contain  a  manhole  with 
fireproof  cover  properly  weighted,  but  not  fastened,  placed  immediately 
above  .the  supply  and  feed  connections  and  the  manhole  in  top  of  the  tank. 

Where  found  impractical  to  set  the  bottom  of  the  tank  three  (3)  feet  below 
the  floor  of  the  cellar  or  lowest  story,  the  tank  shall  rest  on  steel  or  masonry 
supports,  and  the  bottom  of  the  tank  shall  be  at  least  one  (1)  foot  above  the 
floor  of  the  enclosure,  and  the  enclosure  wall  and  floor  as  above  specified 
shall  be  unpierced  and  the  space  below  the  horizontal  centre  line  of  the  tank 
and  within  the  enclosure  formed  by  the  surrounding  unpierced  walls  shall 
have  a  capacity  of  at  least  sixty  (60)  per  cent,  of  the  capacity  of  the  tank. 

The  space  within  the  enclosure  surrounding  the  tank  shall  be  at  all  times 
vented  to  the  air  outside  of  the  building  by  iron  or  other  fireproof  conduit 
at  least  two  and  one-half  (2>£)  inches  diameter,  connecting  the  enclosure 
at  a  point  just  above  the  floor  level,  and  which  shall  finish  above  the  street 
surface  with  proper  connection  at  that  point  to  permit  the  Fire  Department 
to  flood  the  enclosure. 

A  separate  similar  vent  without  Fire  Department  connection  shall  enter 
the  enclosure  just  below  its  ceiling. 

Rule  6.  Capacity  of  Tanks. — In  existing  or  new  buildings  of  non-fireproof 
construction  no  fuel  oil  service  tank  containing  over  ten  thousand  two 
hundred  (10,200)  gallons,  and  in  buildings  of  fireproof  construction  no  tank 
containing  over  twenty  thousand  (20,000)  gallons,  shall  be  placed  in  any 
single  portion  of  the  cellar  or  lowest  story  unless  such  portion  be  separated 
from  the  rest  of  the  cellar  by  walls  of  masonry  or  reinforced  concrete  with 
openings  protected  by  automatic  fireproof  doors,  with  sills  placed  high 
enough  above  the  cellar  floor  to  contain  capacity  of  tank  located  therein,  in 
addition  to  the  enclosure  as  already  specified  for  the  tank,  and  such  portion 
be  ventilated  to  the  outer  air.  More  than  one  such  single  tank  may  be 
installed  if  enclosed  and  separated  as  above. 

When  tanks  are  buried  so  that  the  top  of  the  roof  over  the  enclosure  wall  is 
level  with  the  cellar  floor,  the  capacity  of  any  such  tank  may  be  increased  by 
one  hundred  (100)  per  cent. 

Rule  7.  Service  Tanks  Located  Outside  of  Buildings  Within  Fire 
Limits. — Within  the  fire  limits,  tanks  to  contain  oil  for  use  on  the  premises, 


428  FUEL  OIL  AND  STEAM  ENGINEERING 

and  of  a  capacity  and  at  distances  specified  below,  may  be  placed  above 
ground  outside  of  the  building  if  such  tank  does  not  exceed  fifteen  (15)  feet 
in  height  above  the  surface  of  the  ground  and  if  completely  enclosed  in  the 
same  manner  as  provided  for  in  Rule  5. 

Distance  to  nearest 

building  in  feet  Capacity 

not  exceeding  in  gallons 

40 71,400 

30... 40,800 

20 30,600 

10 20,400 

5.. 10,200 

If  such  service  tanks  are  entirely  buried  and  roofed  below  the  surface  of  the 
ground,  the  capacity  in  gallons  may  be  increased  by  two  hundred  (200) 
per  cent. 

Rule  8.  Outside  General  Storage  Fuel  Oil  Tanks  Located  Above  Ground 
Within  the  Fire  Limits. — Such  general  storage  tanks  located  within  the  fire 
limits  shall  not  exceed  twenty-five  (25)  feet  in  height,  shall  be  built  of  metal, 
and  shall  be  surrounded  with  a  dike  of  unpierced  masonry  or  reinforced 
concrete  not  less  than  four  (4)  feet  in  height,  with  a  capacity  of  at  least  that 
of  the  tank  to  be  protected.  The  walls  and  floor  of  such  dikes  must  be 
continuous,  and  oilproof  and  waterproof,  and  must  not  be  built  within  ten 
(10)  feet  of  the  walls  of  the  tank.  If  tanks  are  placed  in  battery  the  dikes 
shall  be  rectangular  in  shape,  and  the  dike  wall  separating  them  as  well  as 
the  dike  wall  within  one  hundred  (100)  feet  of  any  structure,  shall  be  carried 
up  as  a  fire  stop  to  a  height  of  four  (4)  feet  above  the  head  of  the  tank  and 
coped  with  stone  or  concrete,  and  any  openings  in  walls  above  the  dike 
shall  have  automatic  fireproof  doors. 

The  capacity  of  any  such  single  general  storage  tank  within  the  fire  limits 
shall  not  exceed  one  hundred  thousand  (100,000)  gallons,  and  the  gross 
capacity  of  storage  shall  not  exceed  the  following  tables: 

To  line  of  adjoining 
property   or  nearest 

building  (feet)  Gallons 

75 100,000 

100 150,000 

150 250,000 

200 * 500,000 

Such  general  storage  tanks  may  have  extra  fill  and  emptying  connections 
as  the  Fire  Commissioner  may  determine. 

Rule  9.  Outside  General  Storage  Fuel  Oil  Tanks  Located  Outside  the 
Fire  Limits. — Such  general  storage  tanks  shall  be  protected  by  dikes  and 
fire  stops  as  provided  under  Rule  8,  shall  not  exceed  thirty-five  (35)  feet  in 
height  above  the  ground,  and  may  be  constructed  either  of  metal  or  of 
concrete  reinforced  with  steel  in  order  to  resist  the  oil  pressure. 


RULES  AND  REQUIREMENTS 


429 


If  built  of  concrete,  the  walls  and  floor  of  such  tanks  shall  be  continuous 
and  shall  be  not  less  than  eight  (8)  inches  thick,  mixed  in  the  proportion  of 
1 :  1^2  : 3  graded  and  mixed  in  accordance  with  the  requirements  of  Chapter  5, 
Code  of  Ordinances.  The  walls  shall  be  of  sufficient  thickness  so  that  the 
tensile  stress,  disregarding  the  steel  reinforcement,  shall  not  exceed  OIK; 
hundred  and  fifty  (150)  pounds  per  square  inch.  The  horizontal  and 
vertical  reinforcement  shall  be  properly  proportioned  and  placed  to  provide 
for  expansion  and  shrinkage  without  leakage,  and  the  stress  in  the  steel  shall 
not  exceed  ten  thousand  (10,000)  pounds  per  square  inch. 

As  soon  as  the  concrete  has  hardened  sufficiently  to  be  self-sustaining,  the 
forms  shall  be  removed  and  all  cavities  filled  with  a  one  to  one  (1:1)  mortar 
thoroughly  rubbed  in  and  all  irregularities  trowelled  smooth. 

The  concrete  shall  harden  at  least  twenty-eight  (28)  days  before  use,  and 
the  surface  of  the  floor  and  the  interior  surface  of  the  walls  shall  be  protected 
by  coating  with  a  sodium  silicate  solution  or  other  equally  good  protection  to 
prevent  oil  coming  in  contact  with  the  concrete. 

The  maximum  gross  capacity  of  any  such  single  tank  when  situated 
outside  the  fire  limits  shall  not  exceed  two  hundred  and  fifty  thousand 
(250,000)  gallons,  but  the  gross  storage  capacity  may  be  double  that  specified 
in  the  tables  under  Rule  8;  and  when  such  tanks  are  placed  at  least  two  hun- 
dred and  fifty  (250)  feet  from  the  line  of  adjoining  property  or  the  nearest 
building,  the  gross  capacity  may  be  unlimited. 

Rule  10.  Material  and  Construction  of  Tanks. — 1.  All  fuel  oil  storage 
within  the  fire  limits  shall  be  constructed  of  wrought  iron,  galvanized 
steel,  basic  open  hearth  or  electric  steel  plates  of  gauge  corresponding  to  the 
capacity  as  specified  in  the  following  tables : 


Capacity  in  gallons 


500. . . 

1,000.  .  . 

5,000.  .  . 
10,000.  .  . 
20,000.  .  . 
30,000.  .  . 


TANKS  PLACED  UNDERGROUND 

Thickness  of  material 
U.  S.  gauge 

14 

12 


TANKS  PLACED  ABOVE  GROUND  (Horizontal) 


inch 
inch 
inch 


Maximum  diameter  in  feet 


Thickness  of  material 
U.  S.  Gauge 


Heads 

Shell 

5                                        

7 

10 

g                                                 

Y±  inch 

7 

H                                                         

%  inch 

}/±  inch 

430 


FUEL  OIL  AND  STEAM  ENGINEERING 


TANKS  PLACED  ABOVE  GROUND  (Vertical) 
,     Thickness  of  Material,  U.  S.  Gauge 


Diameter 
feet 

Top 

Top 
ring 

2d  ring 
from 
top 

3d  ring 
from 
top 

4th  ring 
from 
top 

5th  ring 
from 
top 

6th  ring 
from 
top 

Bot- 
tom 

40  and 

less 

10 

7 

7 

7 

5 

3 

2 

10 

45 

10 

7 

7 

7 

5 

3 

1 

10 

50 

10 

7 

7 

7 

4 

1 

0 

10 

55 

10 

7 

7 

6 

3 

1 

2-0 

10 

60 

10 

7 

7 

5 

2 

0 

2-0 

10 

65 

10 

7 

7 

5 

1 

0 

3-0 

10 

70 

10 

7 

7 

4 

1 

2-0 

4-0 

10 

75 

10 

7 

7 

4 

1 

2-0 

4-0 

10 

80 

10 

7 

7 

3 

0 

3-0 

5-0 

10 

2.  Tanks  of  greater  capacity  than  above  shall  be  proportionately  heavier 
and  of  sufficient  thickness  to  safely  hold  the  contents. 

3.  All  joints  shall  be  riveted  and  caulked,  brazed,  welded,  or  made  by 
some  equally  satisfactory  process,   and  the  tanks  braced  sufficiently  to 
withstand  all  stresses  due  to  transportation  or  use.     All  riveted  joints  shall 
have  an  efficiency  of  not  less  than  sixty  (60)  per  cent. 

4.  The  top  cover  shall  be  of  the  same  material  as  used  in  the  construction 
of  the  tank,  permanently  secured  to  the  tanks  without  other  openings  than 
provided  for  in  these  rules.     A  safety  valve  shall  be  installed  on  all  tanks 
placed  outside  of  buildings. 

5.  All  outlets  and  inlets  shall  be  through  the  top  or  cover  of  the  tank, 
except  for  the  clean-out  plug  as  provided  for  under  Rule  2,  and  in  general 
storage  tanks  a  water  drain  not  exceeding  one  (1)  inch  diameter  may  be 
permitted. 

6.  All  metal  tanks  shall  be  thoroughly  coated  on  the  outside  with  tar, 
asphaltum,  or  other  suitable  rust-resisting  protection.     When  buried  in  soil 
impregnated  with  corrosive  materials,  steel  tanks  shall  be  entirely  covered 
with  a  two-inch  thickness  of  cement  mortar  or  shall  be  of  heavier  metal  in 
addition  to  being  protected  as  specified. 

7.  All  above  ground  storage  tanks  exceeding  two  hundred  thousand 
( 200, 000)  gallons  capacity  shall  be  provided  with  approved  explosion  hatches 
having  a  combined  area  of  not  less  than  one  and  one-half  (1J^)  per  cent,  of 
the  roof  area  of  the  tank. 

8.  All  tanks  shall  be  tested  and  must  withstand  a  pressure  of  not  less  than 
twenty-five  (25)  pounds  per  square  inch  shop  test. 

Rule  11.  Vent  and  Fill  Pipes. — 1.  Each  fuel  oil  tank  shall  be  provided 
with  a  separate  steel  vent  pipe  and  a  separate  steel  fill  pipe  of  at  least  two  (2) 
inches  diameter  placed  in  the  top  of  the  tank.  The  vents  for  enclosure 
around  tank  shall  be  as  specified  under  Rule  5. 


RULES  AND  REQUIREMENTS  431 

2.  Vent  pipes  for  fuel  oil  tanks  located  in  the  lower  story  or  buried  under 
buildings   shall  be  run  to  a  point  outside  the  building,  above  the  street 
surface  and  at  least  twelve  (12)  feet  above  the  fill  pipe  and  shall  terminate 
in   a  weatherproof   hood   or   a  gooseneck,  protected  with  non-corrodable 
screens  of  not  less  than  thirty  by  thirty  (30  X  30)  nickel  mesh  or  equivalent. 
Such  vent  shall  not  be  located  within  five  (5)  feet  either  vertically  or  hori- 
zontally of  a  window  or  other  opening  or  an  exterior  stairway  or  fire  escape. 

3.  The  receiver  terminal  of  fill  pipes  shall  be  located  in  a  metal  box  or 
casting  provided  with  means  for  locking  and  the  delivery  terminal  shall  be 
connected  through  the  top  of  the  tank  at  a  point  furthest  remote  from  the 
vent. 

Rule  12.  Fuel  Oil  Feed  Systems. — 1.  Systems  fed  by  gravity  or  force 
systems  between  tank  and  pump  shall  not  be  permitted. 

2.  Pump  suction  feed  systems  only  will  be  approved  and  anti-syphon 
system  must  be  provided* 

Rule  13.  Pumps  and  Piping. — 1.  Feed  pumps  for  fuel  oils  shall  be  of 
approved  design,  so  arranged  that  dangerous  pressures  will  not  obtain  in 
any  part  of  the  system  and  shall  be  located  outside  of  enclosure  walls  around 
storage  tanks,  but  so  placed  as  to  be  accessible  at  all  times,  and  provision 
shall  also  be  made  for  remote  control.  They  shall  be  installed  in  duplicate 
when  directed  by  the  Fire  Commissioner  and  shall  be  provided  with  a  by-pass 
to  permit  the  draining  of  the  oil  for  repairs. 

A  separate  hand  pump  shall  be  provided  for  starting  purposes. 

2.  Oil  conveying  pipes  shall  be  carried  above  the  tank  outlet;  if  laid  under- 
ground after  leaving  the  tank  to  be  carried  in  a  separate  trench  enclosed  in 
fireproof  or  non-conducting  material.     They  shall  be  of  extra  heavy  stand- 
ard wrought  iron,  steel  or  brass  pipe  with  substantial  fittings  and  not  less 
than  one-half  (jHO  inch  in  size  and  if  covered  it  shall  be  with  asbestos  or 
other  approved  fireproof  material.     Overflow  pipes  shall  be  at  least  one 
size  larger  than  supply  pipes  and  shall  be  carried  back  to  the  receiver 
terminal. 

3.  All  connections  shall  be  tight  with  well-fitted  joints.      Unions  shall 
have  at  least  one  face  made  of  brass  with  conically-faced  seats. 

4.  Connections  leading  to  outside  tanks  shall  be  laid  below  the  frost  line 
and  shall  not  be  located  near  or  placed  in  same  trench  with  piping  other 
than  steam  lines  for  heating.     All  pipes  leading  to  the  surface  of  the  ground 
shall  be  cased  or  jacketed  to  prevent  loosening  or  breakage.     Openings  for 
pipes  through  outside  walls  below  the  ground  level  shall  be  securely  cemented 
and  made  oil-tight. 

5.  Piping  shall  be  run  as  directly  as  possible,  without  sags,  and  be  properly 
supported  to  allow  for  expansion,  contraction,  jarring  and  vibration  and 
draining. 

6.  Piping  between  any  separated  oil  container  or  using  parts  of  the  equip- 
ment, should  be  laid  as  far  as  practicable  outside  of  the  building,  under- 
ground, and  inside  piping  in  a  trench  with  metal  cover  or  protected  by  not 
less  than  three  (3)  inches  of  concrete. 

7.  Piping  under  pressure  must  be  designed  with  a  factor  of  safety  of  not 
less  than  six  (6),  and  shall  in  every  case  be  tested  to  a  pressure  of  not  less 
than  one  hundred  and  fifty  (150)  pounds  after  installation. 


432  FUEL  OIL  AND  STEAM  ENGINEERING 

Rule  14.  Controlling  Valves. — 1.  In  fuel  oil  piping  systems,  readily 
accessible  shut-off  valves  shall  be  provided  in  the  supply  line  of  fuel  oils  as 
near  to  tank  as  practicable,  on  both  sides  of  any  strainer  which  may  bo 
installed  in  pipe  lines,  in  the  main  line  inside  the  building,  at  each  oil  consum- 
ing device,  and  a  gate  valve  in  the  discharge  and  suction  pipes  near  the  pump. 
Provision  shall  be  made  to  insure  the  cessation  of  oil  supply  from  tank  to  the 
burner  when  the  pump  is  not  in  work. 

Rule  15.  Heating. — 1.  All  heating  to  reduce  viscosity  of  fuel  oils  in 
storage  tanks  in  any  building  shall  be  only  by  means  of  hot  water  coils  and 
the  oil  shall  not  be  heated  above  one  hundred  and  forty  (140)  degrees 
Fahrenheit. 

2.  All  outside  pipes  subject  to  freezing  shall  be  protected  with  a  heating 
line  of  steam  or  hot  water. 

Rule  16.  Fuel  Oil  Burners. — 1.  Burners  containing  chambers  which 
allow  dangerous  accumulation  of  gases  or  containing  oil-conveying  pipe 
or  parts  subject  to  intense  heat  or  stoppage  from  carbonization  are 
prohibited. 

2.  Oil  shall  be  supplied  through  orifices  not  larger  than  necessary  to 
supply  sufficient  oil  for  maximum  burning  conditions  when  the  controlling 
valves  are  wide  open. 

3.  The  mechanism  shall  be  so  designed  that,  where  manual  or  automatic 
control  is  provided,  operated  at  some  distance  from  the  burner,  the  flame 
cannot  be  extinguished  except  by  closing  the  main  shut-off  valve  in  line  to 
burner.     Approved  gas-pilot  lights  or  equivalent  will  be  acceptable. 

4.  A  check  valve  of  approved  type  shall  be  installed  in  each  oil,  steam 
and  air  line  near  the  burner. 

5.  Smoke  pipes  shall  be  installed  between  the  burners  and  chimney,  and 
any  dampers  in  smoke  pipes  shall  not  exceed  eighty  (80)  per  cent,  of  the  area 
of  the  pipe.     Necessary  regulation  of  draft  shall  be  accomplished  by  dampers 
in  the  fire  or  ash  pit  doors. 

6.  Burners  shall  be  installed  with  overflow  attachment  so  arranged  that 
surplus  oil  will  drain  by  gravity  from  the  burner  into  a  substantially  con- 
structed reservoir.     Such  reservoir  shall  be  constructed  of  brass,  copper  or 
galvanized  iron  plate  not  less  than  No.  18  U.  S.  gauge  in  thickness  and  shall 
be  provided  with  a  vent  pipe  with  weatherproof  hood  leading  outside  the 
building. 

7.  The  supply  of  oil  and  air  or  steam  for  atomizing  shpll  be  interlocked,  so 
that  if  the  steam  or  air  should  fail  the  oil  will  be  automatically  shut  off. 

Rule  17.  Fuel  Oil  Fire  Extinguishing  Equipment. — 1.  Every  tank  with  a 
capacity  of  over  ten  thousand  (10,000)  gallons  shall  be  equipped  with  a 
system  of  steam  pipes,  blanketing  gas  or  other  approved  system  for  use  in 
case  of  fire,  so  arranged  and  installed  as  to  adequately  protect  surrounding 
property. 

2.  When  steam  is  used,  the  steam  supply  pipe  shall  not  be  less  than  one- 
half  0^)  inch  in  size,  the  boilers  shall  be  conveniently  located,  and  shall  be 
controlled  by  valves  outside  the  tank  enclosure. 

Rule  18.  General  Devices. — All  devices  used  in  connection,  with  oil- 
burning  apparatus,  such  as  indicators,  gauges  and  burners,  shall  be  of  such 
character  as  to  minimize  leakage  and  exposure  of  oil,  and  shall  be  connected 


RULER  AND  REQUIREMENTS  433 

through  substantial  fittings.  Devices  which  are  subject  to  breakage  and 
escape  of  oil  shall  be  prohibited. 

Thermometers  with  large  clear  reading  scales,  placed  in  approved  ther- 
mometer wells  with  screwed  top  connections,  shall  be  installed  at  convenient 
and  prominent  positions  in  the  oil  supply  pipe  lines  between  the  service  tank 
and  the  pumps  and  also  between  the  pumps  and  the  burner,  to  indicate 
the  temperature  of  the  oil. 

Rule  19.  Instruction  Cards. — Cards  giving  complete  instructions  for  the 
care  and  operation  of  the  fuel  oil  system  shall  be  permanently  fixed  near  the 
apparatus. 

Rule  20.  Operation  of  Plant. — Such  fuel  oil-burning  plants  may  be 
operated  only  by  a  licensed  engineer  or  by  a  licensed  operator  who  shall  be 
a  citizen  of  the  United  States,  who  can  read  and  write  the  English  language, 
and  who  is  familiar  with  the  practical  working  of  such  plant,  as  evidenced 
by  the  certificate  of  the  Fire  Commissioner. 

Rule  21.  Installation. — No  installation  of  fuel  oil  plants  shall  be  com- 
menced until  after  the  approval  of  plans  by  the  Fire  Commissioner,  which 
plans  shall  be  submitted  to  him  for  examination,  together  with  the  certificate 
of  the  Superintendent  of  Buildings  that  the  proposed  construction  of  the 
enclosure  and  the  location  of  tanks  is  in  accordance  with  the  requirements  of 
the  Building  Code  and  of  these  Rules. 

Adopted,  Nov.  6,  1919. 

JOHN  P.  LEO,  Chairman. 
WM.  WIRT  MILLS,  Secretary. 


28 


APPENDIX  IV 
FUEL  OIL  DATA— APPROXIMATE  VALUES 

1  barrel  of  oil  42  gallons 

1  barrel  oil  at  16°Baume     approximately  336  Ibs. 

1  gallon  oil  at  16°Baume       approximately      8  Ibs. 

Specific  heat  of  fuel  oil  . .  .- 0.498  to  0.5 

Coefficient  of  expansion  of  California  oils: 

0.0004    per  1°F. 
0.00072  per  1°C. 

Heating  value  of  fuel  oil  (approximate) : 

Heat  units  in  1  pound  oil 18,500  B.t.u. 

Heat  units  in  1  gallon  oil  (16°Baume) 148,000  B.t.u. 

Heat  units  in  1  barrel  oil  (16°Baum4) 6,216,000  B.t.u. 

Latent  heat  of  vaporization  of  oil 100-130  B.t.u.  per  Ib. 

Viscosity. 

COMPARISON  OF  VISCOSITY  SCALES.     (Approximate.) 

Engler,  deg.  Saybolt,  sees. 

1  30 

10  350 

20  680 

40  1360 

60  2050 

200  7000 

Viscosity  of  water  at  60°F.-1°  Engler  or  30  sec.  Saybolt 

Viscosity  of  Coalinga  (Cal.)  oil  of  16°Be".   gravity. 

Temp:  °F.                                        Viscosity  °Engler 

110  15 

120  12 

125  10 

140  7 

180  3 

212  2 

Evaporation  from  and  at  212°  per  Ib.  oil  at  78  per  cent,  efficiency 15  Ib. 

Actual  evaporation  from  100°F.  feed  temperature  to  150  Ib.  pressure 
per  Ib.  oil  at  78  per  cent,  efficiency 13  Ib. 

1  ton  of  coal  (2000  Ib.)  containing  11,500  B.t.u.  per  Ib.  is  equivalent  to  3 
barrels  of  oil. 

434 


FUEL  OIL  DATA— APPROXIMATE  VALUES  435 

Oil  required  to  produce  one  boiler  horsepower 2.^  lb.  per  hr. 

Boiler  horsepower  produced  from  1  barrel  oil  per  hr 134. 

1  boiler  horsepower  =  34>2  lb.  water  evaporated  from  and  at  212°F.  per  hr. 
]  boiler  horsepower  =  33,479  B.t.u.  per  hr. 
1  mech.  horsepower  =  33,000  ft.-lb.  per  min. 

=    2,545  B.t.u.  per  hr. 
1  boiler  horsepower  =  13.14  mech.  horsepower. 

Air  required  per  pound  oil  for  complete  combustion : 

Theoretical  requirements 13      lb. 

15  per  cent,  excess  air  (14  %  CO2) 15      lb. 

50  per  cent,  excess  air  (10%  CO2) 19>2  lb. 

Steam  required  to  atomize  1  lb.  oil 0 . 25 — 0 . 5  lb. 

Per  cent,  of  total  steam  generated  required  to  atomize  oil. .      2% — 4% 
Heat  transfer  in  oil  heaters  (heated  by  condensing  steam): 

B.t.u.  per  hr.  per  sq.  ft.  per  deg.  difference  in  tempera- 
ture. .  15  B.t.u.— 50  B.t.u. 


436 


FUEL  OIL  AND  STEAM  ENGINEERING 


TABLE  1. — OIL  STANDARDS 
1  barrel  =  42  U.  S.  gallons  =  5.6146  cu.  ft. 


Degrees 
Baume 

Specific 
gravity 

Weight  per 
barrel,  Ib. 

Lb.  per 

U.  S.  gallon 

B.t.u.  per 
Ib. 

B.t.u.  per 
barrel 

10 

1.000 

350.194 

8.338 

18,380 

6,436,566 

11 

0.993 

347.707 

8.279 

18,440 

6,411,717 

12 

0.986 

345.256 

8.220 

18,550 

6,387^236 

13 

0.979 

342.840 

8.163 

18,560 

6,363,110 

14 

0.972 

340.458 

8.106 

18,620 

6,339,328 

15 

0.966 

338.112 

8.050 

18,680 

6,315,932 

16 

0.959 

335.801 

7.995 

18,740 

6,292,911 

17 

0.952 

333.525 

7.941 

18,800 

6,270,270 

18 

0.946 

331.248 

7.887 

18,860 

6,247,337 

19 

0.940 

329.042 

7.834 

18,920 

6,225,474 

20 

0.933 

326.838 

7.787 

18,980 

6,203,347 

21 

0.927 

324.700 

7.731 

19,040 

6,182,288 

22 

0.921 

322  .  564 

7.680 

19,100 

6,160,972 

23 

0.915 

320.427 

7.629 

19,160 

6,139,381 

24 

0.909 

318.361 

7.580 

19,220 

6,118,898 

25 

0.903 

316.295 

7.531 

19,280 

6,098,168 

26 

0.897 

314.264 

7.482 

19,340 

6,077,866 

27 

0.892 

312.268 

7.435 

19,400 

6,067,999 

28 

0.886 

310.307 

7.388 

19,460 

6,038,574 

29 

0.881 

308.346 

7.341 

19,520 

6,018,914 

30 

0.875 

306.420 

7.296 

19,580 

5,999,704 

31 

0.870 

304.529 

7.251 

19,640 

5,980,950 

32 

0.864 

302  .  638 

7.206 

19,700 

5,961,969 

33 

0.859 

300.781 

7.161 

19,760 

5,934,433 

34 

0.854 

298,960 

7.118 

19,820 

5,925,387 

35 

0.848 

297  .  139 

7.075 

19,880 

5,907,123 

36 

0.843 

295.353 

7.032 

19,940 

5,889,339 

37 

0.838 

293  .  567 

6.990 

20,000 

5,871,340 

38 

0.833 

291.817 

6.948 

20,060 

5,853,849 

39 

0.828 

290.101 

6.907 

20,120 

5,836,832 

40 

0.824 

288.385 

6.866 

20,180 

5,819,609 

41 

0.819 

286.704 

6.826 

20,204 

5,802,889 

42 

0.814 

285.058 

6.787 

20,300 

5,786,677 

43 

0.809 

283.377 

6.746 

20,360 

5,769,556 

44 

0.805 

281  .  766 

6.709 

20,420 

5,753,662 

45 

0.800 

280.155 

6.670 

20,480 

5,737,574 

Sp.  gr.  =  140  -*-  (130  +  deg.  Be.  at  60°F.) 

Weight  of  oil  per  barrel  =  (sp.  gr.)  X  (wt.  per  cu.  ft.  of  water  at  60°F. 
62.372  Ib.)  X  (no.  of  cu.  ft.  per  barrel  =  5.6146). 


FUEL  OIL  DATA— APPROXIMATE  VALUES 


437 


TABLE   2. — DEC.    Bi?.  AND  CORRESPONDING  SPECIFIC  GRAVITIES  OF   OIL, 
POUNDS  PER  GALLON,  AND  GALLONS  PER  PouND1 


Deg. 
Be. 

Specific 
gravity  at 
60°/60°F. 

Lb.  per 

gal. 

Gal.  per 
Ib. 

Deg. 
Be. 

Specific 
gravity  at 
60°/60°F. 

Lb.  per 
gal. 

Gal.  per 
Ib. 

10.0 

1.0000 

8.328 

0.1201 

15.0 

0.9655 

8.041 

0.1244 

10.5 

0.9964 

8.299 

0  .  1205 

15.5 

0.9622 

8.013 

0.1248 

11.0 

0.9929 

8.269 

0  .  1209 

16.0 

0  .  9589 

7.986 

0  .  1252 

11.5 

0.9894 

8.240 

0.1214 

16.5 

0.9556 

7.959 

0.1256 

12.0 

0.9859 

8.211 

0.1218 

17.0 

0.9524 

7.931 

0.1261 

12.5 

0.9825 

8.182 

0  .  1222 

17.5 

0.9492 

7.904 

0.1265 

13.0 

0  .  9790 

8.153 

0.1227 

18.0 

0.9459 

7.877 

1  .  1270 

13.5 

0.9756 

8.125 

0.1231 

18.5 

0.9428 

7.851 

0.1274 

14.0 

0.9722 

8.096 

0.1235 

19.0 

0.9396 

7.825 

0.1278 

14.5 

0.9688 

8.069 

0.1239 

19.5 

0.9365 

7.799 

0.1282 

20.0 

0.9333 

7.772 

0.1287 

26.0 

0.8974 

7.473 

0  .  1338 

20.5 

0.9302 

7.747 

0.1291 

26.5 

0.8946 

7.449 

0.1342 

21.0 

0.9272 

7.721 

0.1295 

27.0 

0.8917 

7.425 

0.1347 

21.5 

0.9241 

7.696 

0  .  1299 

27.5 

0.8889 

7.402 

0.1351 

22.0 

0.9211 

7.670 

0  .  1304 

28.0 

0.8861 

7.378 

0.1355 

22.5 

0.9180 

7.645 

0  .  1308 

,  28.5 

0.8833 

7.355 

0.1360 

23.0 

0.9150 

7.620 

0.1313 

29.0 

0  .  8805 

7.332 

0.1364 

23.5 

0.9121 

7.595 

0.1317 

29.5 

0.8777 

7.309 

0.1368 

24.0 

0.9091 

7.570 

0.1321 

30.0 

0.8750 

7.286 

0.1373 

24.5 

0.9061 

7.546 

0.1325 

30.5 

0.8723 

7.264 

0.1377 

25.0 

0.9032 

7.522 

0.1330 

31.0 

0.8696 

7.241 

0.1381 

25.5 

0.9003 

7.497 

0.1334 

31.5 

0.8669 

7.218 

0.1385 

32.0 

0  .  8642 

7.196 

0  .  1390 

38.0 

0.8333 

6.939 

0.1441 

32.5 

0.8615 

7.173 

0.1394 

38.5 

0  .  8309 

6.918 

0.1446 

33.0 

0.8589 

7.152 

0.1398 

39.0 

0.8284 

6.898  . 

0.1450 

33.5 

0.8563 

7.130 

0.1403 

39.5 

0.8260 

6.877 

0.1454 

34.0 

0.8537 

7.108 

0  .  1407 

40.0 

0  .  8235 

6.857 

0.1459 

34.5 

0.8511 

7.087 

0.1411 

40.5 

0.8211 

6.837 

0.1463 

35.0 

0.8485 

7.065 

0.1415 

41.0 

0.8187 

6.817 

0.1467 

35.5 

0  .  8459 

7.044 

0.1420 

41.5 

0.8163 

6.797 

0.1471 

36.0 

0.8434 

7.022 

0.1424 

42.0 

0.8140 

6.777 

0  .  1476 

36.5 

0  .  8408 

7.001 

0.1428 

42.5 

0.8116 

6.758 

0.1480 

37.0 

0.8383 

6.980 

0.1433 

43.0 

0.8092 

6  .  738 

0.1484 

37.5 

0.8358 

6.960 

0.1437 

43.5 

0.8069 

6.718 

0.14S9 

44.0 

0.8046 

6.699 

0  .  1493 

50.0 

0  .  7778 

6.476 

0.1544 

44.5 

0  .  8023 

6.680 

0.1497 

50.5 

0  .  7756 

6.458 

0.1548 

1  United  States  Bureau  of  Standards,  United  States  standard  tables  for  petroleum  oils: 
Circular  57,  Jan.  29,  1916,  p.  57. 


438 


FUEL  OIL  AND  STEAM  ENGINEERING 


TABLE  3. — TEMPERATURE  CORRECTIONS  TO  READINGS  OF  SPECIFIC  GRAVITY 
HYDROMETERS  IN  AMERICAN  PETROLEUM  OILS  AT  VARIOUS  TEMPERATURES1 

[Standard  at  60°/60°F.] 


Observed 
temperature, 
°F. 

Observed  specific  gravity 

0.650 

0.700 

0.750 

0.800 

0.850 

0.900 

0.950 

Subtract  from  observed  specific  gravity 

30 
32 
34 
36 
38 

0.016 
0.015 
0.014 
0.013 
0.012 

0.015 
0.014 
0.013 
0.012 
0.011 

0.014 
0.013 
0.012 
0.011 
0.010 

0.012 
0.012 
0.011 
0.010 
0.009 

0.011 
0.011 
0.010 
0.009 
0.008 

0.011 
0.010 
0.010 
0.009 
0.008 

0.011 
0.010 
0.010 
0.009 
0.008 

40 
42 

44 
46 
48 

0.0105 
0.0095 
0.0085 
0.0075 
0.0065 

0.0095 
0.0085 
0.0075 
0.0065 
0.0060 

0.0090 
0.0080 
0.0070 
0.0060 
0.0055 

0.0080 
0.0070 
0.0065 
0.0055 
0.0050 

0.0075 
0.0065 
0.0060 
0.0050 
0.0045 

0.0070 
0.0065 
0.0060 
0  .  0050 
0.0045 

0.0070 
0.0065 
0.0055 
0.0050 
0.0040 

50 
52 
54 
56 

58 

60 
62 
64 
66 
68 

0.0050 
0.0040 
0.0030 
0.0020 
0.0010 

0.0050 
0.0040 
0.0030 
0.0020 
0.0010 

0.0045 
0.0035 
0.0025 
0.0020 
0.0010 

0.0040 
0.0030 
0.0025 
0.0015 
0.0005 

0.0035 
0.0030 
0.0020 
0.0015 
0.0005 

0.0035 
0.0030 
0.0020 
0.0015 
0.0005 

0.0035 
0.0030 
0.0020 
0.0015 
0  .  0005 

Add  to  observed  specific  gravity 

0.0000 
0.0010 
0.0020 
0.0030 
0.0040 

0.0000 
0.0010 
0.0020 
0.0030 
0.0040 

0.0000 
0.0010 
0.0015 
0.0025 
0.0035 

0.0000 
0.0005 
0.0015 
0.0025 
0.0030 

0.0000 
0.0005 
0.0015 
0.0020 
0.0030 

0.0000 
0.0005 
0.0015 
0.0020 
0.0030 

0.0000 

70 

72 
74 
76 
78 

0.0050 
0.0060 
0.0070 
0.0080 
0.0090 

0.0050 
0.0055 
0.0065 
0.0075 
0.0085 

0.0045 
0.0050 
0.0060 
0.0070 
0.0080 

0.0040 
0.0045 
0.0055 
0.0065 
0.0070 

0.0040 
0.0045 
0.0050 
0.0060 
0.0065 

0.0035 
0  .  0040 
0.0050 
0.0055 
0.0065 

80 
82 
84 
86 
88 

0.010 
0.011 
0.012 
0.013 
0.014 

0.009 
0.010 
0.011 
0.012 
0.013 

0.008 
0.009 
0.010 
0.011 
0.012 

0.008 
0.008 
0.009 
0.010 
0.011 

0.007 
0.008 
0.009 
0.009 
0.010 

0.007 
0.007 
0.008 
0.009 
0.010 

90 
92 
94 
96 

98 

0.015 
0.016 
0.017 
0.018 
0.019 

0.014 
0.015 
0.016 
0.016 
0.017 

0.013 
0.013 
0.014 
0.015 
0.016 

0.012 
0.012 
0.013 
0.014 
0.015 

0.011 
0.011 
0.012 
0.013 
0.014 

0.010 
0.011 
0.012 
0.013 
0.013 

100 
102 
104 
106 
108 

0.020 
0.021 
0.022 
0.023 
0.024 

0.018 
0.019 
0.020 
0.021 
0.022 

0.017 
0.018 
0.018 
0.019 
0.020 

0.015 
0.016 
0.017 
0.017 
0.018 

0.014 
0.015 
0.016 
0.016 
0.017 

0.014 
0.015 
0.015 
0.016 
0.017 

110 
112 
114 
116 
118 

0.025 
0.026 
0.027 
0.028 
0.029 

0.023 
0.024 
0.025 
0.026 
0.026 

0.021 
0.022 
0.022 
0.023 
0.024 

0.019 
0.020 
0.020 
0.021 
0.022 

0.018 
0.019 
0.019 
0.020 
0.021 

0.017 
0.018 
0.019 
0.019 
0.020 

120 

0.030 

0.027 

0.025 

0.023 

0.022 

0.021 

This  table  is  calculated  from  the  same  data  as  Table  1,  Circular  57,  Bureau  of  Standards. 


FUEL  OIL  DATA— APPROXIMATE  VALUES 


439 


TABLE  4. — TEMPERATURE  CORRECTIONS  TO  READINGS  OF  BAUM£  HYDRO- 
METERS' IN    AMERICAN    PETROLEUM    OILS    AT    VARIOUS    TEMPERATURES l 

[Standard  at  60°F.;  modulus  140.] 


Observed 
tempera- 
ture, °F. 

Observed  deg.  B6. 

20.0           30.0           40.0           50.0 

60.0           70.0 

80.0           90.0 

Add  to  observed  deg.  B£. 

30 

1.7 

2.0 

2.4 

3.0 

3.7 

4.3 

5.0 

5.7 

32 

1.6 

1.9 

2.3 

2.8 

3.4 

4.0 

4.7 

f>  .  3 

34 

1.5 

1.8 

2.1 

2.6 

3.1 

3.7 

4.3 

4.9 

36 

1.4 

1.6 

2.0 

2.4 

2.9 

3.4 

4.0 

4.6 

38 

1.3 

1.5 

1.8 

2.2 

2.6 

3  .  1 

3.6 

4.2 

40 

1.2 

1.4 

1.6 

2.0 

2.4 

2.8 

3.2 

3..S 

42 

1.1 

1.2 

1.5 

1.8 

2.2 

2.5 

2.9 

3.4 

44 

0.9 

1.1 

1.3 

1.6 

2.0 

2.2 

2.6 

3.0 

46 

0.8 

0.9 

1.1 

1.4 

1.7 

1.9 

2.3 

2.7 

48 

0.7 

0.8 

0.9 

1.2 

1.4 

1.6 

2.0 

2.3 

50 

0.6 

0.7 

0.8 

1.0 

1.2 

1.4 

1.6 

1.9 

52 

0.5 

0.6 

0.7 

0.8 

1.0 

1.1 

1.3 

1.5 

54 

0.3 

0.4 

05 

0.6 

0.8 

0.9 

1.0 

1.1 

56 

0.2 

0.3 

0.3 

0.4 

0.5 

0.6 

0.6 

0.7 

58 

0.1 

0.1 

0.1 

0.2 

0.3 

0.3 

0.3 

0.4 

Subtract  from  observed  deg.  Be". 

60 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

62 

0.1 

0.1 

0.1 

0.2 

0.2 

0.3 

0.3 

0.4 

64 

0.2 

0.3 

0.3 

0.4 

0.4 

0.6 

0.6 

0.7 

66 

0.3 

0.4 

0.5 

0.6 

0.7 

0.8 

0.9 

1.0 

68 

0.5 

0.6 

0.6 

0.7 

0.9 

1.1 

1.3 

1.4 

70 

0.6 

0.7 

0.8 

0.9 

1.1 

1.4 

1.6 

1.7 

72 

0.7 

0.8 

0.9 

1.1 

1.3 

1.6 

1.9 

2.1 

74 

0.8 

0.9 

1.1 

1.3 

1.6 

1.8 

2.2 

2.5 

76 

0.9 

1.1 

1.3 

1.5 

1.8 

2.1 

2.5 

2.8 

78 

1.0 

1.2 

1.4 

1.7 

2.0 

2.4 

2.8 

3.1 

80 

.1 

1.3 

1.5 

1.8 

2.2 

2.0 

3.1 

3.5 

82 

.2 

1.4 

1.7 

2.0 

2.5 

2.9 

3.4 

3.9 

84 

.3 

1.5 

1.8 

2.2 

2.7 

3.2 

3.7 

4.3 

86 

.4 

1.7 

2.0 

2.4 

2.9 

3  4 

4.0 

4.6 

88 

.6 

1.8 

2.1 

2.6 

3.1 

3.7 

4   2 

4.9 

90 

.7 

2.0 

2.3 

2.7 

3.3      '           .9 

4   5 

5.2 

92 

.8 

2.1 

2.4 

2.9 

3  .5                .2 

4.S 

5.6 

94 

.9 

2.2 

2.6 

3.1 

3  .  S                 .4 

.">    1 

5  .  9 

96 

2.0 

2.3 

2.7 

3  .  3 

4.0                 .C> 

r>  .  -i 

()  .  3 

98 

2.1 

2.4 

2.9 

3.4 

•1  .2 

.9 

">.7 

(>  .  (i 

100 

2.2 

2.6 

3.0 

3  .  (» 

4.4 

.1 

(i.o 

0.9 

102 

2.3 

2.7 

3.2 

3.8 

4.6 

.4 

(i  .  3 

7.2 

104 

2.4 

2.9 

3.3 

4.0 

4.8 

.  7 

(>  .  (> 

7.5 

106 

2.5 

3.0 

3.5 

4.2 

5  0 

.9 

(i  9 

7.9 

108 

2.7 

3.1 

3.6 

4.3 

5.2 

.2 

7.2 

S.2 

110 

2.8 

3.2 

3.7 

4.4 

5.4 

6.4 

7.5 

8.5 

112 

2.9 

3.3 

3.9 

4.6 

5.6 

6.7 

7.7 

8.8 

114 

3.0 

3.4 

4.0 

4.7 

5.8 

6.9 

7.9 

9.1 

116 

3.1 

3.6 

4.1 

4.9 

6.0 

7.1 

8.2 

9.4 

118 

3.2 

3.7 

4.3 

5.1 

6.2 

7.3 

8.5 

9.8 

120 

3.3 

3.8 

4.4 

5.3 

6.4 

7.5 

8.8 

10.1 

1  This  table  is  calculated  from  the  sajne  data  as  Table  2,  Circular  57,  Bureau  of  Standards. 


440 


FUEL  OIL  AND  STEAM  ENGINEERING 


TABLE  5. — TEMPERATURE  CORRECTIONS  TO  APPARENT  SPECIFIC  GRAVITIES 
OF  PETROLEUM  OiLS1 

[This  table  gives  the  correction  to  be  added  to  apparent  specific  gravities  of  heavy  petroleum 
oils  (fuel  oils,  lubricating  oils,  etc.),  at  temperatures  of  60°  to  210°F.  to  give  the  true  spe- 
cific gravity  of  the  oil  at  60°/60°F.  It  is  assumed  that  the  hydrometer  or  pycnometer 
used  is  of  glass  having  a  coefficient  of  cubical  expansion  of  0.000023  per  degree  centigrade, 
and  is  correct  at  60°F.] 


Observed 
temperature, 
°F. 

Observed  specific  gravity 

0.850 

0.860 

0.870 

0.880 

0.890 

0.900 

0.910 

0.920 

0.930 

0.940 

0.950 

0.960 

Add  to  observed  specific  gravity  to  give  true  specific  gravity  at  60°/60°F. 

60 
62 
64 
66 

68 

0.000 
0.001 
0.002 
0.002 
0.003 

0.000 
0.001 
0.002 
0.002 
0.003 

0.000 
0.001 
0.002 
0.002 
0.003 

0.000 
0.001 
0.002 
0.002 
0.003 

0.0000.000 
0.001  0.001 
0.0020.002 
0.0020.002 
0.0030.003 

0.000 
0.001 
0.002 
0.002 
0.003 

0.0000.0000.0000.0000.000 

o.ooilo.ooi  o.ooi  o.  001  o.ooi 

0.002  0.002  0.002  0.002  0.002 
0.00210.0020.0020.0020.002 
0.003  0.003  0.003  0.003  0.003 

70 
72 
74 

76 

78 

0.004 
0.004 
0.005 
0.006 
0.006 

0.004 
0.004 
0.005 
0.006 
0.006 

0.004 
0.004 
0.005 
0.006 
0.006 

0.004 
0.004 
0.005 
0.006 
0.006 

0.0040.004 
0.0040.004 
0.0050.005 
0.  00610.006 
0.  006  0.006 

0.004 
0.004 
0.005 
0.006 
0.006 

0.0040.0040.004 
0.004;0.004,0.004 
0.0050.005'0.005 

o.ooe;o.  006  o.ooe 

0.0060.0060.006 

0.0040.004 
0.  004J0.004 
0.00510.005 
0.0060.006 
0.006i0.006 

80 
82 
84 
86 

88 

0.007 
0.008 
0.009 
0.009 
0.010 

0.007 
0.008 
0.008 
0.009 
0.010 

0.007 
0.008 
0.008 
0.009 
0.010 

0.007 
0.008 
0.008 
0.009 
0.010 

0.007 
0.008 
0.008 
0.009 
0.010 

0.007 
0.007 
0.008 
0.009 
0.010 

0.007 
0.007 
0.008 
0.009 
0.010 

0.007,0.007 
0.00710.007 
0.0080.008 
0.0090.009 
0.0100.010 

0.007 
0.007 
0.008 
0.009 
0.010 

0.007 
0.007 
0.008 
0.009 
0.010 

0.007 
0.007 
0.008 
0.009 
0.010 

90 
92 
94 
96 
98 

0.011 
0.011 
0.012 
0.013 
0.014 

0.011 
0.011 
0.012 
0.013 
0.013 

0.011 
0.011 
0.012 
0.013 
0.013 

0.011 
0.011 
0.012 
0.013 
0.013 

0.0100.010 
0.011  0.011 
0  0120.012 
0.0130.013 
0.0130.013 

0.010 
0.011 
0.012 
0.012 
0.013 

0.010 
0.011 
0.012 
0.012 
0.013 

0.010 
0.011 
0.012 
0.012 
0.013 

0.010 
0.011 
0.012 
0.012 
0.013 

0.010 
0.011 
0.012 
0.012 
0.013 

0.010 
0.011 
0.012 
0.012 
0.013 

100 
105 
110 
115 
120 

0.014 
0.016 
0.018 
0.020 
0.022 

0.014 
0.016 
0.018 
0.020 
0.021 

0.014 
0.016 
0.018 
0.020 
0.021 

0.014 
0.016 
0.018 
0.020 
0.021 

0.0140.014 
0.01610.016 
0.017'0.017 
0.019|0.019 
0.021  0.021 

0.014 
0.016 
0.017 
0.019 
0.021 

0.014 
0.016 
0.017 
0.019 
0.021 

0.014 
0.016 
0.017 
0.019 
0.021 

0.014 
0.016 
0.017 
0.019 
0.021 

0.014 
0.016 
0.017 
0.019 
0.021 

0.014 
0.016 
0.017 
0.019 
0.021 

125 
130 
135 
140 
145 

0.023 
0.025 
0.027 
0.028 
0.030 

0.023 
0.025 
0.027 
0.028 
0.030 

0.023 
0.025 
0.026 
0.028 
0.030 

0.023 
0.025 
0.026 
0.028 
0.030 

0.0230.023 
0.02510.024 
0.0260.026 
0.0280.028 
0.0300.030 

0.023 
0.024 
0.026 
0.028 
0.029 

0.023 
0.024 
0.026 
0.028 
0.029 

0.023 
0.024 
0.026 
0.028 
0.029 

0.022 
0.024 
0.026 
0.027 
0.029 

0.022 
0.024 
0.026 
0.027 
0.029 

150 
155 
160 
165 
170 

0.032 
0.034 
0.035 
0.037 
0.039 

0.032 
0.033 
0.035 
0.037 
0.039 

0.032 
0.033 
0.035 
0.037 
0.038 

0.031 
0.033 
0.035 
0.037 
0.038 

0.031 
0.033 

a!  085 

0.036 
0.038 

0.031 
0.033 
0.035 
0.036 
0.038 

0.031 
0.033 
0.034 
0.036 
0.038 

0.031 
0.033 
0.034 
0.036 
0.038 

0.031 
0.033 
0.034 
0.036 
0.038 

0.031 
0.033 
0.034 
0.036 
0.037 

0.031 

175 
180 
185 
190 
195 

200 
205 
210 

0.040 
0.042 
0.044 
0.045 
0.047 

0.049 
0.051 
0  .  052 

0.040 
0.042 
0.044 
0.045 
0.047 

0.049 
0.050 
0.052 

0.040 
0.042 
0.043 
0.045 
0.047 

0.048 
0.050 
0.052 

0.040 
0.041 
0.043 
0.045 
0.047 

0  048 
0  .  050 
0.051 

0.040 
0.041 
0.043 
0.045 
0.046 

0.048 
0.050 
0.051 

0.040 
0.041 
0.043 
0.044 
0.046 

0.048 
0.050 
0.051 

0.039 
0.041 
0.043 
0.044 
0.046 

0.048 
0.049 
0.051 

0.039 
0.041 
0.043 
0.044 
0.046 

0.048 
0.049 
0.051 

0.039 
0.041 
0.042 
0.044 
0.046 

0.047 
0.049 
0.051 

0.039 
0.041 

1  For  more  complete  oil  tables,  see  Circular  57,  Bureau  of  Standards. 


FUEL  OIL  DATA— APPROXIMATE  VALUES 


441 


TABLE  6. — TEMPERATURE  CORRECTIONS  TO  APPARENT  DEC;.  BAUME  OF 
PETROLEUM,  OILSI 

This  table  gives  the  corrections  to  be  subtracted  from  the  apparent  deg.  B6.  of  heavy 
petroleum  oils  (fuel  oils,  lubricating  oils,  etc.)  at  temperatures  from  60°  to  210°F.  to  give 
the  true  deg.  B6.  at  60°F.  (modulus,  140).  It  is  assumed  that  the  hydrometer  is  of 
glass  having  a  coefficient  of  cubical  expansion  of  0.000023  per  deg.  C.,  and  is  correct  at 
60°F.l 


Observed  degrees  Be. 

Observed 
temperature, 

14 

16 

18 

20 

22 

24 

26 

28 

30 

32 

34 

36 

Subtract  from  observed  deg.  Be.  to  obtain  true  deg.  B6.  at  60°F. 

60 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

62 

0.1 

0.1 

0.1 

0.1 

0.1 

0.1 

0.1 

0.1 

0.1 

0.1 

0.1 

0.1 

64 

0.2 

0.2 

0.2 

0.2 

0.2 

0.2 

0.3 

0.3 

0.3 

0.3 

0.3 

0.3 

66 

0.3 

0.3 

0.3 

0.3 

0.3 

0.3 

0.4 

0.4 

0.4 

0.4 

0.4 

0.4 

68 

0.4 

0.4 

0.4 

0.5 

0.5 

0.5 

0.5 

0.5 

0.6 

0.6 

0.6 

o.e 

70 

0.5 

0.5 

0.5 

0.6 

0.6 

0.6 

0.6 

0.6 

0.7 

0.7 

0.8 

0.8 

72 

0.6 

0.6 

0.6 

0.7 

0.7 

0.7 

0.7 

0.7 

0.8 

0.8 

0.9 

0.9 

74 

0.7 

0.7 

0.7 

0.8 

0.8 

0.8 

0.9 

0.9 

0.9 

0.9 

1.0 

1.1 

76 

0.8 

0.8 

0.8 

0.9 

0.9 

0.9 

1.0 

1.0 

1.1 

1.1 

1.2 

1.2 

78 

0.9 

0.9 

0.9 

1.0 

1.1 

1.1 

1.1 

1.2 

1.2 

1.2 

1.3 

1.4 

80 

1.0 

1.0 

1.1 

.1 

1.2 

.2 

1.2 

1.3 

.3 

.3 

1.4 

1.5 

82 

1.1 

1.2 

2 

1.3 

.3 

1.V5 

1.4 

.4 

.  5 

1.5 

1.6 

84 

1.3 

1.3 

.3 

1.4 

.4 

1.5 

1.5 

.5 

.6 

1.7 

1.8 

86 

1.4 

1.4 

.4 

1.5 

.5 

1.6 

1.6 

.7 

.8 

1.8 

1.9 

88 

1.5 

1.5 

.6 

1.6 

.7 

1.7 

1.8 

.8 

.9 

2.0 

2.0 

90 

1.6 

1.6 

.7 

1.7 

.8 

1.8 

1.9 

2.0 

2.0 

2.1 

2.1 

92 

1.7 

1.7 

.8 

1.8 

.9 

1.9 

2.0 

2.1 

2.1 

2.2 

2.3 

94 

1.8 

1.8 

.9 

1.9 

2.0 

2.0 

2.1 

2.2 

2.2 

2.3 

2.4 

96 

1.9 

1.9 

2.0 

2.0 

2.1 

2.2 

2.3 

2.3 

2.4 

2.5 

2.5 

98 

2.0 

2.0 

2.1 

2.2 

2.2 

2.3 

2.4 

2.4 

2.5 

2.6 

2.7 

100 

2.1 

2.2 

2.2 

2.3 

2.3 

2.4 

2.5 

2.6 

2.7 

2.7 

2.8 

105 

2.4 

2.4 

2.5 

2.6 

2.6 

2.7 

2.8 

2.9 

3.0 

3.1 

3.2 

110 

2.6 

2.7 

2.8 

2.8 

2.9 

3.0 

3.1 

3.2 

3.3 

3.4 

3.5 

115 

2.9 

2.9 

3.0 

3.1 

3.2 

3.3 

3.4 

3.5 

3.6 

3.8 

3.9 

120 

3.1 

3.2 

3.3 

3.4 

3.5 

3.6 

3.7 

3.8 

3.9 

4.0 

4.2 

125 

.  3.4 

3.5 

3.6 

3.7 

3.8 

4.0 

4.1 

4.2 

4.3 

4.5 

130 

'.'.'.'.  3.7 

3.8 

3.9 

4.0 

4.1 

4.3 

4.4 

4.5 

4.7 

4.8 

135 

.  3.9 

4.1 

4.2 

4.3 

4.4 

4.6 

4.7 

4.8 

5.0 

5.2 

140 

'•  4.2 

4.3 

4.4 

4.6 

4.7 

4.8 

5.0 

5.1 

5.3 

5.5 

145 

1  4.4 

4.6 

4.7 

4.8 

5.0 

5.1 

5.3 

5.4 

5.6 

5.8 

150 

.  4.7 

4.8 

5.0 

5.1 

5.2 

5.4 

5.6 

5.7 

5.9 

6.1 

155 

4.9 

5.1 

5.2 

5.4 

5.5 

5.7 

5.9 

6.0 

6.2 

6.4 

160 

5.3 

5.5 

5.6 

5.8 

6.0 

6.2 

6.3 

6.5 

6.7 

165     J  

5.6 

5.7 

5.9 

6.1 

6.3 

6.5 

6.6 

6.8 

7.0 

170 



5.8 

6.0 

6.2 

6.3 

6.5 

6.7 

6.9 

7.1 

7.3 

175 

6.0 

6.2 

6.4 

6.6 

6.8 

7.0 

7.2 

7.4 

7.6 

180 

6  3 

6.5 

6.6 

6.8 

7.1 

7.3 

7.5 

7.7 

8.0 

185 

6.5 

6.7 

6.9 

7.1 

7.3 

7.6 

7.8 

8.0 

8.3 

190 

6.8 

7.0 

7.2 

7.4 

7.6 

7.8 

8.1 

8.3 

8.6 

195 

7.0 

7.2 

7.4 

7.6 

7.9 

8.1 

8.4 

8.6 

8.9 

200 

7.5 

7.7 

7.9 

8.1 

8.4 

8.6 

8.9 

9.2 

205 

7.7 

7.9 

8.2 

8.4 

8.7 

8.9 

9.2 

9.5 

210 

8.0 

8.2 

8.4 

8.7 

8.9 

9.2 

9.5 

9.8 

For  more  complete  oil  tables  see  Circular  57,  Bureau  of  Standards. 


442  FUEL  OIL  AND  STEAM  ENGINEERING 

AVERAGE  SPECIFIC  HEAT 

All  fuel  oils  are  mixtures  of  many  hydrocarbon  compounds,  each  with  its 
own  specific  heat.  When  the  heat  capacity  of  an  oil  is  desired  it  is  the 
practice  to  accept  the  average  specific  heat  of  a  similar  oil  as  determined  by 
experiment.  Table  7  gives  average  values  for  different  petroleums. 

TABLE  7. — SPECIFIC  HEAT  CAPACITIES1 

Specific 

heat 
capacity 

Petroleum  ether  at  -180°C 0.452 

Petroleum  ether  at  -100°C 0.445^ 

Petroleum  ether  at  0°C 0.419* 

Kerosene,  21-58°C 0.511 

Kerosene,  18-99°C 0 . 498 

Paraffin  solid,  -20°  to  3°. 0.377 

Paraffin  solid,  -19°  to  20° ' 0. 525 

Paraffin  solid,  25°  to  30° 0. 589 

Paraffin  solid,  35°  to  40° 0 . 622 

Paraffin  liquid,  52.4°  to  55° 0. 700 

Specific 
Crude  oils:  gravity 

Japan 0.862  0.453 

Pennsylvania 0 . 810  0 . 500 

Russia 0.908  0.435 

California •.  .  .  .  0.960  0.398 

Bustenari 0 . 842  0 . 462 

Campina,  0.8  per  cent,  paraffin     0.859  0.467 

Campina,  3.2  per  cent,  paraffin       0.854  0.457 

Mabery  and  Goldstein2  give  the  following  formula  for  calculating  specific 
heats : 

Specific  heat  X  molecular  weight   _   „ 
Number  of  atoms  in  molecule 

For  the  hydrocarbons  of  the  paraffin  series,  CnH2n+2,  the  value  of  K  is 

2.28. 

1  Holde,  David,  The  examination  of  hydrocarbon  oils,  1915,  pp.  13  and  17. 

2  Mabery,  C.  F.,  and  Goldstein,  A.  H.,  On  the  specific  heats  and  heat  of 
vaporization  of  the  paraffin  and  methylene  hydrocarbons:  Am.  Chem.  Jour., 
1902,  vol.  28,  pp.  66-78. 


0/L  DATA— APPROXIMATE  VALUES 


443 


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APPENDIX  V 
BRIEF  BIBLIOGRAPHY  ON  FUEL  OIL 

Oil  Fuel — Its  Supply,  Composition  and  Application,  by  Edward  Butter, 
M.I.M.E.  Pub.  by  Charles  Griffin  &  Company,  Ltd.,  London,  3d  Edition, 
1914. 

Oil  Fuel,  by  Ernest  H.  Peabody.  A  paper  presented  at  the  International 
Engineering  Congress,  San  Francisco,  1915. 

•  Industrial  Uses  of  Fuel  Oil,  by  F.  B.  Dunn.     Technical  Publishing  Co., 
S.  F.,  1916,  235  pp. 
•»  The  Science  of  Burning  Liquid  Fuel,  by  William  Newton  Best. 

Liquid  and  Gaseous  Fuels,  by  Vivian  Bryan  Lewes.     Published  by  A.  Con- 
stable &  Co.,  London,  1907. 
*  Liquid  Fuel  and  its  Apparatus,  by  W.  H.  Booth,  London,  1911. 

Elements  of  Fuel  Oil  &  Steam  Engineering,  by  Robert  Sibley  &  C.  H. 
Delany.  Published  by  McGraw-Hill  Book  Co.,  New  York. 

Efficiency  in  the  Use  of  Fuel  Oil,  by  J.  M.  Wadsworth.  Published  by 
U.  S.  Bureau  of  Mines,  Washington,  D.  C. 

Fuel  Oil  in  Industry,  by  Stephen  O.  Andros.  Published  by  Thaw 
Publishing  Company,  Chicago,  111. 


444 


INDEX 


Absolute,  pressure,  22 
temperature,  46 
zero,  46,  58 
Absorption,  heat  of,  110 

of  solutions,  flue  gas  analysis, 

275 

Acceleration,  16 
Accessories,  boiler,  107,  110 
Accumulators,  oil,  423 
Advantages,  of  fuel  oil,  125 

of  mechanical  atomizing,  177 
Air,  admission  to  oil  furnaces,   156 
excess,  377 
leakage,  191 

loss  due  to  moisture  in,  326 
meters,  399 
openings,   oil  furnace,   area  of 

159,  160 
location  of,  159 

regulating,  from  flue  gas  analy- 
sis, 355 

regulation,  106,  189,  191 
required,  excess,  259 

for    combustion,     103,     105, 

279,  283 
excess  air,  284 
per  pound  fuel,  285 
ratio  of  actual  to  theoreti- 
cal, 291 

theoretical,  284 
per  pound  oil,  259,  435 
theoretical,  259 

spaces   in    Scotch   boiler,    *160 
supplied,    calculated   from   flue 

gas  analysis,  288 
formulas  for,  288,  289 
per  pound  of  fuel,  286 
supply  for  oil  furnaces,  103,  105 
theoretical  requirements,  435 
Altitude,  chimney,  connections  for, 

262,  263 
effect  of,  on  draft,  255 


Alaskan  coal,  388 
Alcohol  thermometers,  37 
American     Institute    of     Electrical 
Engineers,  70,  351,  358,  414 
American    Society    of     Mechanical 
Engineers,    70,    219,    289, 
308,    311,    321,    329,    332, 
333,    359,  414 

Analysis,    flue    gas,    106,    191,    271 
of  oil,  310,  443 
steam  tables,  57 
Analyzer,  flue  gas,  *275 
Apparatus,    auxiliary,    *394,    *395, 

*398 

economy  measuring,  *197,  *396 
Orsat,  *273 

Apparent  specific  gravity,  tempera- 
ture corrections,  440 
Appliances,  oil  burning,  202 
Arizona  Power  Company,  *216,  *217, 

*218,  352 

Arniboldi,  Jarvis,  230 
Arrangement    of    baffles    in    boiler, 

*345 

Artificial  draft,  268 
Ash  pit  doors,  draft  regulated  by, 

339 

ASME  power  test  committee,   332 
Asphaltum  in  petroleum,  129 
Atmosphere,  pressure  in,  60 
Atomization,  heat  for,  321 
loss  due  to,  325 
steam  used  in,  302,  310 
Atomizer  type,  oil  burners,  166 
Atomizing,     mechanical     (see     Me- 
chanical atomizing) 
steam,  device  for  limiting,  348 
method  of  measuring,  369,  374 
per  cent  of  total,  435 
per  pound  oil,  *375 
pressure,  *377 

quantity  required  per  pound 
oil,  435 


445 


446 


INDEX 


Atomizing,  steam,  regulation  of,  194 
with  automatic  firing,  361 
with  hand  firing,  361 
Attachments,  oil  storage  tanks,  205 
Atwater    Mahler    fuel    calorimeter, 

*244 

Austrian  Oil,  443 
Automatic,  control,  399 
measurer,  water,  *298 
regulators,  215,  344 

gain  in  efficiency  from,  399 
Merit,  *219,  *220,  *341 
Moore,    ,*216,     *217,     *218, 
*331,    360,    384    (see    also 
Moore    automatic    regula- 
tors) 

Witt,  *215 
Auxiliaries,     electric     driven,     398 

steam  driven,  398 
Auxiliary,    apparatus,    *394,    *395, 

*398 

oil  tanks,  425 
turbo-generator,  398 


13 


Babcock  &  Wilcox,  boilers,  *7,  118, 

*161,  *164 
Company,   180,   184,   187,  441, 

443 

marine  boiler,  *121,  *122 
mechanical  atomizing  burners, 

184,  *185,  *186 
installed  under,  *178 
Back  shot  burner,  161 
Badenhausen  boiler,  120 
Baffles,   arrangement  of,   in  boiler, 

*345 

boilers,  198 

effect    of,    on    draft    loss,    266 
Barges,  oil,  424 
Barometer,  27,  28,  *262 

corrections  for,  29 
Barrel,  B.t.u.  in,  434 
gallons  in,  434 
steam  calorimeter,  82 
weight  of  oil  per,  434 
Battery     of     15     oil-fired     boilers, 
*115 


Baume,  Antoine,  227 

degrees,     temperature     correc- 
tions to,  439,  441 
hydrometers,  *227,  *228 
scale,  227 

confusion  from,  228 

for     liquids,     heavier     than 

water,  227 

lighter    than    water,     228 
Best  Oil  burners,  *171 
Bibliography,  444 

Blowing    down    boilers,     144,     198 
Board   of    Standards   and  Appeals, 

426 
Boilers,  6 

accessories,  107,  110 
and   Economizer  efficiency, 
Long  Beach  Steam  Plant,  372 
arrangement  of  baffles  in,  345 
Babcock  &  Wilcox,  *7,  118,  *161, 

*164 

marine,     *121,  *122 
Badenhausen,  120 
baffles,  198 

battery  of  15  oil-fired,  *115 
blowing  down,  144,  198 
classification,  115 
cleaning,  145,  198 
cooling,  145 

cylinder  oil  kept  out,  145 
draft  loss,  in,  267 

through,  340,  372 
drum,  115 
Edgemoor,  121 
efficiency,  310 

Arizona  plants,  359 

as  a  steaming  mechanism,  328 

defined,  329 

Long    Beach    Steam    Plant, 

*371 

net,  327,  332 

New  Cornelia  Copper  Com- 
pany, 360 
Erie  City,  120 
externally  fired,  116 
feeding  water  to,  196 
fire  tube,  7,  116 
firing,  scientifically,  200 
up,  144 


INDEX 


447 


Boilers,  foaming,  144 
forcing  of,  195 
four  pass,  120 
front,  typical,  *60 
Hartford    Inspection    &    Insur- 
ance Company,  142 
heat  absorbed  by,  320,  321,  322 
Heine,  121 
high  pressure,  115 
horizontal,  117 
horsepower,    68,    70,     71,    435 

per  barrel  oil,  435 

to  compute,  76 
inspection  of,  141 
installation,  safety  in,  *413 
internally  fired,  116 
Keeler,  121 
kerosene  used  in,  145 
low  water,  144 
marine,  122 
Milwaukee,  *116 
net    heat    absorbed     by,     322 
number  of  oil  burners  per,  372 
oil  burning  (see  also  Oil  burning 

boilers) 

oil  required  to  keep  hot,  359, 378 
operation,  141 

precautions,  142 

report,  *342,  344 
Parker,  *119,  118 
radiation  from,  359,  378 
repairs  under  pressure,  144 
return  tubular,  *116 
room,    efficiency    with    Moore 
Automatic  regulators,  361 

oil  fired,  *107 

rules,  for  efficient  operation  of, 
189 

for  safety,  141 
Rust,  120 

safe  operation  of,  141 
Scotch,  122 
shell,  107 

rules  for  computing  strength 
of,  148,  149,  150,  151,  152 

strength  of,  148 
shutting  down,  146 
steam,    principle   of   operation, 
109 


Boilers,  Stirling,  120,  *161,    *162 

strength  of,  147 

surface  blows,  144 

test,  gage,  *142 

pump,*143    (see  also     Boiler 
tests) 

three  pass,  120 

Thorny  croft,  123 

time  required  to  start  up,  379 

tubes,  115 

variable  load  on,  196 

vertical,  117 

water,  circulation,  118 
tube,  7,  116 

working  pressure,  141 
Boiler  tests,  beginning,  309 

code  for  oil  fired,  332,  333,  336 

comparative  results,  349 

data  and  results  of,  333 

duration  of,  309 

for  efficiency, 309 

general  log,  318 

graphic  log,  *318 

instruction  for,  308 

log  sheet,  314,  *315,  *316,  *317 

Long  Beach  Steam  Plant,  370 

object  of,  307 

observations  necessary,  311 

on  swinging  load,  378 

overload,  311 

plotting  of  data,  319 

pressure  readings,  312 

principal  data  and  results  of,  336 

quick  steaming,  311 

starting  up  cold,  379 

stopping,  309 

tabulated  data,  347 

tabulation  of  data,  314,  316 

taking  of  data,  307 

temperature  readings,  312 

use  of  in  increasing  efficiency, 
337 

with    mechanical   atomizing 
burners,  358 

with  steam  atomizing  burners, 

357 

Borneo  Oil,  443 
Boyle's  law,  *42,  44 
British  thermal  unit,  44 


448 


INDEX 


B.t.u.,  44 

in  barrel,  434 
of  oil  per  barrel,  436 
of  oil  per  pound,  436 
per  K.  W.  hour,  353 
per  pound  of  oil,  443 
Bureau  of  Mines,  U.  S.,  235,  242,  299 
Bureau  of  Standards,  U.  S.,  39,  229, 

437,  438,  439,  440,  441 
Burning  point  of  petroleum,  *124 
Bursting  pressure,  147 

of  riveted  joint,  152 
Bustenari  Oil,  442 
Burners,  back  shot,  161 
classification  of,  166 
flow  of  oil  through,  379 
front  shot,  161 

housings    around,    furnace    ar- 
rangement, *346 
inside  mixer,  166 
location  of,  161 

mechanical  atomizing  (see  Me- 
chanical Atomizing  Burn- 
ers,       also        Mechanical 
atomizing  oil  burners) 
number  required  for  mechanical 

atomizing  burners,  187 
oil,     104,     192,     (see    also    Oil 

burners) 
outside  mixer,  168 


Calibration  of  orifice  for  measuring 

steam,  *306 

California,  oil,  387,  442,  443 
fields,  *386 
pipe  lines,  *386 
Railroad  Commission,  411 
State  Mining  Bureau,  411 
Caloric,  31,  42 
Calorific  value  of  oil,  443 

of  petroleum,  127,  133 
Calorimeter,  fuel,  244  (see  also  Fuel 

calorimeter) 
Parr,  *245,  *246,  (see  also  Parr 

calorimeter) 

steam  (see  Steam    calorimeters) 
Calorists,  42 
Campina  oil,  442 


Capacity  and  location  of  oil  tanks, 

416,  419 

of  mechanical  atomizing  burn- 
ers, 182 

of  oil  burning  boilers,  393 
of  oil  tanks,  427 
Carbon  monoxide,  flue  gas  analysis, 

274 

loss  due  to,  324 
Carnot  cycle,  395 
Carriers,  oil,  424 
Centigrade  thermometers,  32,  35 
Centrifugal  pumps,  111,  399 
Centrifuge,  *235 
Chamber  type  oil  burners,  166 
Changing  from  coal  to  oil,  182 
Charles  Law,  45 

Checkerwork,  arrangement,  oil  fur- 
naces, *156,  157 
furnace  arrangement,  *346 
Check -valves,  112 
Chemical,  energy,  21 

properties  of  petroleum,  126 
steam  calorimeter,  86 
Chimney,  106 

correction  for  altitude,  262 
design,  *260 
cost  of,  260 

example  for  sea  level,  259 
for  least  cost,  260 
draft  required  at  base  of,  268, 

(see  also  Draft) 
example  of  design,  264 
friction  of  gases  in,  255 
gas     analysis     (see     Flue     gas 

analysis) 

gases,  loss  due  to,  323 
of  small  diameter,  262 
rule  for  altitude  correction,  263 
size    of,    for    draft,    257,    258, 

268 

Circulating  water  cycle,  9 
City  of  Seattle,  *224 
Classification  of  boilers,  115 
of  burners,  166 
of  petroleum,  125 
Cleaning  boilers,  145,  198 
Cleaners,  tube,  146 
Closed  heaters,  6 


INDEX 


449 


CO2,  content,  273 

flue  gas  analysis,  273 
maximum  possible,  294 
recorder,  *272,  279 

flue  gas  analysis,  *271 
Coal,  140,  388 
Alaskan,  388 

burning  plant,  design  of,  389 
changing  from,  to  oil,  221 
comparison  with  oil,  *222 
draft  required  for,  265 
efficiency  from,  221 
heating  value  of,  221 
moisture  in,  223 
pulverized,  388 
stoker  fired,  388 
Code  for  boiler  tests,  oil  fired  boilers, 

332,  333,  336 

Coefficient  of  expansion,  oil,  206,  434 
Coen,     mechanical     atomizing     oil 

burners,  *176 
Colombian  Oil,  139 
Color,  of  petroleum,  125,  126 

temperature  by,  36 
Column,  mercury,  23 
water,  *110,  112 
Combustion,  air   required  for,  103, 

105,  279,  283 
excess  air,  284 
per  pound  fuel,  285 
ratio  of  actual  to  theoretical, 

291 

theoretical,  284 
chamber,     large     oil     burning 

boilers,  393 
data,  286 

incomplete,  loss  due  to,  323 
of  oil  by  mechanical  atomizing, 

182 
of  one  pound  of  oil,  293 

table  of,  294 
oxygen  required  for,  284 
Commercial      furnaces,       Hammel, 

164,  *165 
large,  164 
material  of,  160 
Peabody,  *161,  162 
Peabody-Hammel,  *163 
volumetric  proportion  of,  160 
29 


Comparison  of  coal  with  oil,  *222 
Composition  of  oil,  443 
Computations  of  Westphal  Balance, 

233 
Condenser,  8 

jet,  9 

surface,  9 
Conduction,  107 

Confusion  from  Baum6  scale,  227 
Conservation  and  study  of  fuel  oil, 
helpful  factors  in,  411 

of  energy,  21 
Construction,  oil,  burners,  425 

furnaces,  103 

tanks,  416,  421,  429 
Consumption,  of  fuel  oil,  124 

of  petroleum,  138 
Content,  CO2,  273 
Control,  automatic,  399 

damper,  348 
Controller,  master,  *220 
Controlling  valves  for  oil  tanks,  418 
Convection,  107 
Conversion,  of  pressure,  27 

rule  for,  flue  gas  analysis,  282 
Conveyors,  oil,  424 
Cooking,  oil  for,  424 
Cooling,  of  boilers,  145 

pond,    New    Cornelia    Copper 

Company,  *366 
Corbet,  Darrah,  351,  358 
Corrections  for  barometer,  29 
Corrosion  from  petroleum,  129 
Cost,  chimney  design,  260 
Crude  oil,  hydrogen  content,  275 
Cycle,  Carnot,  395 

circulating  water,  9 

oil,  10 

steam,  3 
Cylinder  oil,  keep  out  of  boiler,  145 

D 

Dahl     mechanical     atomizing     oil 

burners,  175 
Damper,  control,  348 

draft,  regulated  by,  339 
required  at,  372,  *373 
leakage  passed,  348 
regulator,  *218 


450 


INDEX 


Data,  and  results,  boiler  tests,  333 

boiler  tests 

plotting  of,  319 
tabulation  of,  314,  316 

combustion,  286 

economy,  table  of,  348 

oil,  434 

tabulated,  boiler  tests,  347 

taking  of,  in  boiler  tests,  307 
Davy,  42,  43 

experiments  of,  42 
Definition  of  fuels,  103 
Degrees   Baume,   temperature    cor- 
rections to,  439,  441 
Density,  gas,  46 

of  petroleum,  126 

specific,  of  steam,  60 
Design,  of  chimney,  example,  264 

of  coal  burning  plant,  389 

power  plant,  present  status,  386 
Determining    moisture    in    oil,    236 
Detroit  Edison  Company,  399 
Device  for  limiting  atomizing  steam, 

348 
Diagram,  of  draft,  *258 

oil  production,  *391 

power  plant,  *4 

temperature  heat,  53 
Differential  draft  gage,  *105 
Disadvantages,  of  fuel  oil,  125 

of  mechanical  atomizing,  179 
Distillation,  oil,  239 

process  of,  239 
Doolittle,  H.  L.,  368 
Draft,  artificial,  268 

at  Long  Beach  Plant,  *376 

available,  372 

diagram  of,  *258 

effect  of  altitude  on,  255 

excess  air  varying  with,  377 

for        mechanical       atomizing 
burners,  176 

forced,  268,  269 

formula,  for  available,  256 
for  theoretical,  254 

gage,  105,  *280 
differential,  *105 
with  five  outlets,  *201 

in  inches  of  water,  253 


Draft,  in  furnace,  265 

in  pounds  per  square  foot,  253 
induced,  268,  270 

with  economizers,  270 
law  of  pressures  in,  251 
loss,  266 

effect  of  baffles  on,  266 
formula  for,  256     . 
friction  losses  in  chimney, 255 
in  boilers,  267 
in  flues,  267 

in  water  tube  boilers,  266 
limitations  of,  266 
through  boiler,  372 
regulated  by,  ash  pit  doors,  339 

damper,  339 
regulation  of,  106 
relation,  between  furnace  burner 
and  draft,  oil  burning,  340 
to  furnace  and  burner,  340 
required  at  base  of  chimney,  268 
at  damper,  372,  *373 
for  coal,  265 
for  fuel  oil,  265 
loss  of,  159 
mechanical    atomizing,     176, 

188 

oil  burning,  339 

size  of  chimney  for,  257,  258,  268 
table  of,  257 
theoretical,  252,  *255 
theory  of,  251 

total  available  required,  267 
varying,  376 

Drooling  type  oil  burners,  166 
Drum,  boiler,  115 

mud,  113 
Dry  saturated  steam,  75,  79 

quality  of,  79 
Dry  vacuum  pump,  9 
Dulong's  formula,  242 
Duplex  pump,  111 
Duration  of  boiler  tests,  309 
Dwight    CO2    indicator,     flue    gas 
analysis,  *277 

E 

Economizers,  6,  104,  270,  394 
induced  draft  with,  270 


INDEX 


451 


Economy,  best,  New  Cornelia  Cop- 
per, Company,  364 
data,  348 

table  of,  348 
in  oil  burning,  351 
maintaining,       New      Cornelia 

Copper  Company,  362 
measuring  apparatus,  *197,*396 
Edgemoor  boiler,  121 
Edison  Company,  Detroit,  399 

Southern  California,  *2,  *3,  *6, 
*43,  *46,  *67,  *197,  *202, 
*208,  *210,  *282,  *297, 
*303,  368,  *390,  *394,  *396, 
*398 
Long  Beach  plant,  *83,  *101, 

*102 
Efficiency,    approximate,   from   flue 

gas  analysis,  353 
boiler,  310 

New   Cornelia  Copper  Com- 
pany, 360 
room,  with  Moore  Automatic 

Regulators,  361 
curve,    New    Cornelia    Copper 

Company,   *365 
from  coal,  221 

gain  in,  from  automatic  regu- 
lators, 399 

of  boilers,  at  Arizona  plants,  359 
of    mechanical   atomizing   bur- 
ners, *181 

of  riveted  joint,  150,  154 
oil  burning,  average  plant,  353 
use  of  boiler  tests  in  increasing, 

337 

Electric,     driven     auxiliaries,     398 
Light  Association,  National,  180 
steam  calorimeters,  90 
Electrical,  energy,  21 

Engineers,    American    Institute 
of,     70,     351,     358,     414 
thermometers,  38 
World,  *178,  414 
Electricity,  Journal  of,  414 
Electrification  of  railroads,  140 
Emerson  Fuel  Calorimeter,  *243 
Enclosure  of  oil  tanks,  426 
Energy,  20 


Energy,  chemical,  21 

conservation  of,  21 

electrical,  21 

kinetic,  20 

mechanical,  21 

potential,  20 
Engine,  reciprocating,  8 
Engineers,      Electrical,      American 
Institute  of,  70 

Mechanical,   American   Society 

of,  70 

Engler,  128,  131 
Entropy,  64 

temperature  diagram,  *65 
Equipment,  type  of,  New  Cornelia 

Copper  Company,  360 
Equivalent,  evaporation,  73,  74,  77 

mechanical,  of  heat,  58 
Erie  City  boiler,  120 
Evaporation,  equivalent,  73,  74,  77 

factor  of,  73,  74 

for  dry  saturated  steam,  75 
for  superheated  steam,  76 
for  wet  steam,  75 

latent  heat  of,  97 
Excess  air,  377 

required,  259 

varying  with  draft,  377 
Exhaust  steam,  moisture  in,  397 

utilization  of,  398 
Expansion,  113 

coefficient  of,  oil,  206,  434 

pyrometers,  38 

Explosion    of    charge,    Parr    colori- 
meter, 248 
Externally  fired  boiler,  116 


Factor,  of  evaporation  (see  Evapora- 
tion, factor  of) 

of  safety,  147 

Fahrenheit  thermometers,  32,  34 
Fan  tail  type,  oil  burners,  166 
Feed,  pumps,  422 

water  heaters,  5 

water  pumps,  6,  111 
Fess  Oil  Burners,  168 
Fill  pipes,  430 


452 


INDEX 


Fill  pipes,  for  oil  tanks,  422 

Filters,  oil,  422 

Fire,  extinguishers  for  oil  tanks,  418, 

432 
limits,  oil  tanks  outside  of,  428 

oil  tanks  within,  42.8 
oil,  how  to  light,  196 
tube  boilers,  7,  116 
Underwriters     National   Board 

of,  204 

rules  and  requirements,  415 
Firing,  boilers,  scientifically,  200 

up,  boilers,  144 

First  law  of  thermodynamics,  44 
Flash,  point,  131,  426 
of  oil,  443 
Pennsky-Martens  tester  for, 

131 

test  for  petroleum,  *124 
Flow,  of .  oil  through  orifices,  *  380, 

*381,  *383 
influence  of  temperature  on, 

*383 
of  steam,  302 

Napier's  formula  for,  303 
through  orifice,  303 
Flue  gas,  analysis,  106,  191,  271,  273, 

313 

absorption  solutions,  275 
air  supplied,  calculated  from, 

288 
approximate  efficiency  from, 

353 

by  weight,  279 
carbon  monoxide,  274 
CO2,  content,  273 

recorder,  *271 

Dwight  CO2  indicator,   *277 
for  maximum  efficiency,  340 
from  boilers  in  regular   ser- 
vice, 354,  355 
from  oil,  275 
Hemphel  apparatus,  276 
hydrogen  content,  276 
nitrogen  content,  274 
Orsat  apparatus,  271 
oxygen  content,  274 
pocket  CO2  indicator,  277  *278 
regulating  air  from,  355 


Flue  gas,  relation  of  weight  to  vol- 
ume, 281 

rule  for  conversion,  282 
sum  of  readings,  275 
tabulation  of,  283 
taking  of  gas  samples,  271 
analyzer,     *275 
formula  for,  291 
quantity  per  bbl.  hp.  per  hour, 

259 

weight  of,  per  pound  fuel,  290 
Flues,  draft  loss  in,  267 
Foaming  boilers,  144 
Force,  16 

pound,  16 

Forced  draft,  268,  269 
Forcing  of  boilers,  195 
Formation  of  steam,  52 
Formula,  Dulong's,  242 

for  air  supplied,  288,  289 
for  available  draft,  256 
for  draft  loss,  256 
for  flue  gas,  291 
for  heat  transfer,  109 
for  saturated  steam,  96,  97 
for  specific  heat,  442 
for  steam  constants,  95,  96,  97 
for  superheated  steam,  98,  99 
for  theoretical  draft,  254 
Friction,  in  chimney,  draft  loss,  255 

of  gases  in  chimney,  255 
Front  shot  burner,  161 
Fuel,  387 

air  supplied  per  pound  of,  286 
calorimeter,  244 

Atwater  Mahler,  *244 
Emerson,  *243 
Mahler  bomb,  *245 
Parr,  *245 
definition  of,  103 
liquid,  125 

loss  due  to  water  in,  322 
oil,  advantages  of,  125 
consumption  of,  124 
disadvantages  of,  125 
draft  required  for,  265 
price  fluctuation,  136 
prices  of,  135 
production  of,  135 


INDEX 


453 


Flue  oil,  in  California,  124 
shortage  of  ,-137 
sources  of,  139 
stocks  of,  137 

study  and  conservation  help- 
ful  factors    in,    411 
supply  of,  137 
oxygen  in,  284 
weight  of  flue  gas  per  pound, 

290 

Fundamental  units,  15 
Furnaces,  arrangement,  344 
checkerwork,  *346 
housings      around      burners, 

*346 

oil  burning,  337 
commercial,  159  (see  also  Com- 
mercial furnaces) 
draft  in,  265 
gases,  path  of,  104 
Hammel  Peabody,  360 
interior,  oil  burning,  *338 
oil,     155,     192,     (see    also    Oil 

furnaces) 
Peabody,  *7,  356 


G 


Gage,  boiler  test,  *142 
cocks,  113 
draft,      105      (see     also     Draft 

gage) 

measuring,  oil,  *206 
pressure,  22 
steam,  *22,  *23,  112 
tester,  *19 
water,  112 

Gallons  in  barrel,  434 
Galvanometer,  39 

Gas,  and  Electric  Company,  Pacific, 
*190,  *193,  *203,  *207, 
*225,  *280,  *330,  *342, 
*382,  *392,  *393,  *395, 
397 

density,  46 
flue,  analysis,  106 
natural,  388 
weight,  252 
Gases,  chimney,  loss  due  to,  323 


Gases,  escaping,  effect  of  soot  blowers 

on  temperature  of,  359 
temperature   of,  from  boilers 

in  service,  356 
friction  of,  in  chimney,  255 
furnace,  path  of,  104 
law  of,  46 
velocity  of,  through  water  tube 

boilers,  266 

Gauge  glasses  for  oil  tanks,  423 
Gebhardt,  G.  F.,  256 
Generation,  steam,  107 
Geological  Survey,  U.  S.,  411 
Goldstein,  A.  H.,  442 
Grate  bars,  *346 
Gravity,  of  oil,  227 

readings,   for  temperature  cor- 
rections, 438,  440 
specific,  131,  426,  442 
of  petroleum,  127 


II 


Hammel,   commercial  furnace   164, 

*165 

oil  burners,  166,  *167,  361,  378 

Peabody  furnace,  360 

Hartford    Steam    Boiler    Inspection 

&  Insurance  Company,  142 

Heat,  absorbed  by  boiler,  320,  321, 

322 
balance,  320 

heat  absorbed  by  boiler,  320, 

321,  322 

loss  due  to,  atomization,  325 
burning  hydrogen,  323 
carbon  monoxide,  324 
chimney  gases,  323 
incomplete  combustion, 323 
moisture  in  air,  326 
water  in  fuel,  322 
stray  losses,  326 
summary,  327 
effect  of,  on  petroleum,  126 
for  atomization,  321 
in  steam  generated,  310 
latent,  52,  53,  58 
of  evaporation,  97 
of  petroleum,  127 


454 


INDEX 


Heat,  latent,  of  steam,  62 
laws  of,  107 
localization  of,  160 
mechanical   equivalent    of,    44, 

58 

net  absorbed  by  boiler,  322 
of  absorption,  110 
of  liquid  steam,  61 
of  steam,  total,  55,  63 
of  superheated  steam,  total,  79 
of  water,  specific,  59 
specific,  37 

temperature  diagram,  53 
total,  of  saturated  steam,  96 
transfer,  107,  435 
formula  for,  109 
in  oil  heaters,  435 
rate  of,  110 
Heaters,  closed,  6 
feed  water,  5 
oil,  10,  *207,  *208,  *212 
open,  5 

Heating,  of  oil,  432 
oil  for,  424 

surface  required,  oil  heaters,  213 
value,  higher,  250 
lower,  250 
of  coal,  221 
of  hydrogen,  250 
of  oil,  241,  434 

approximate    formula    for, 

242 

approximate   method,    242 
Dulong's  formula,  242 
graphic  law  for,  *241 
Heine  boiler,  121 

Hemphel  apparatus,  flue  gas  analy- 
sis, 276 
Henning's    formula,    for    saturated 

steam,  97 

for  steam  constants,  97 
High  pressure  boiler,  115 
Holde,  David,  442 
Home-made  oil  burners,  169,  *173 
Horizontal,  boiler,  117 
steam  turbines,  8 
Horsepower,  66,  67,  *69 
boiler,  68,  70,  71,  435 
to  compute,  76 


Horsepower,  mechanical,  70,  435 
quantity,  flue  gas  per  bbl.  per 

hour,  259 
of    oil    burned    per   h.p.  per 

hour,  258 

relationship  of  boiler  and  me- 
chanical, 435 
Hot  well,  5 
Housings   around   burners,    furnace 

arrangement,  *346 
Hydroelectric  power,  1 

shortage  of,  386 
Hydrogen,  content,  crude  oil,  275 

flue  gas  analysis,  276 
heating  value  of,  250 
loss  due  to  burning,  323 
Hydrometers,  Baume",  *227,  *228 

limitations  of,  230 
Hygrometer,  *37 


Ice,  51 

Impurities  in  petroleum,  132 

Incomplete  combustion,  loss  due  to, 

323 

Indicator,  oil  tanks,  418,  422 
Induced  draft,  268,  270 
Injector,  111 

type,  oil  burners,  166 
Inside  mixer,  burners,  166 
Inspection  of  boilers,  141 
Inspiration  Copper  Company,  *331 
Installation,  New  York  City,  rules 

for,  426 

of  boilers,  safety  in  *413 
of  mechanical  atomizing  burn- 
ers under  B.  &  W.  boilers, 
*178 

of  oil  burners,  425 
of  oil  burning  equipment,  rules 

for,  415,  426 
of  oil  burning  plants,  433 
of  oil  tanks,  rules  for,  415 
Instruction  for  boiler  tests,  308 
Instruments,  recording,  200 
Interconnected  steam  electric  power 

plants,  392 
Internally  fired  boiler,  116 


INDEX 


455 


Isolated  Steam  electric  power  plants, 

391 
Italian  oil,  443 


Jacobus,  D.  S.  180,  182 

Japan  oil,  442 

Java  oil,  443 

Jet  condenser,  9 

Joint,  riveted  (see  Riveted  joint) 

Joule,  43 

Joule's  equivalent,  44 

Journal  of  Electricity,  414 


K 


K.W.  hours  per  barrel  oil,  *353 

at  Arizona  plants,  359 

at  New  Cornelia  Copper  Com- 
pany, 364 
Keeler  boiler,  121 
Keeping  records,  200 
Kent,  William,  17 
Kerosene,  442 

used  in  boilers,  145 
Kier,  124 

Kinetic  energy,  20 
Kingsbury,  137 

Koerting,  mechanical  atomizing  oil 
burners,  *174,  175 

oil  heaters,  *214 


Lamp  oil  in  petroleum,  129 
Latent  heat,  52,  53,  58 

of  evaporation,  97 

of  oil,  434 
Laws,  of  heat,  107 

of  gases,  46 

of  motion,  Newton's,  15 

of  thermodynamics,  42 
Leaky  oil  burners,  *169,  382 
Leakage,  air,  191 

passed,  damper,  348 
LeConte,  J.  N.,  242 
Leland  Stanford,  Jr.,  University,  411 
Length,  unit  of,  15 


Lewis,  N.  E.,  180,  182 

Light   &    Power   Company,    Pacific, 

382 

Lighting  oil  fire,  196 
Limitations  of  draft  loss,  266 
Linde's     formula     for     superheated 

steam,  98 
Liquid  fuels,  125 
Load  on  boilers,  variable,  196 
Localization  of  heat,  160 
Location,  of  burners,  161 
of  oil  tanks,  426 
of  steam  electric  power  plants, 

389 

Lockett  oil  burners,  *172 
Locomotives,  use  of  oil  in,  140 
Lodi  mechanical  atomizing  burners, 

184 

Log,  general,  boiler  tests,  318 
graphic,  boiler  tests,  *318 
sheet,    boiler   tests,    314,    *315, 

*316,  *317 

Long    Beach    Plant,   draft   at,    *376 
Southern       California      Edison 
Company,   *83,   *101,   *102 
stack  temperature,  *374 
Long    Beach    Steam    Plant,    boiler, 
and  economizer  efficiency, 
372 

efficiency,  *371 
tests,  370 

description  of  plant,  368 
method  of  testing,  369 
pressure  loss  in  superheat,  375, 

*376 

Loss  due  to,  atomization,  325 
burning  hydrogen,  323 
carbon  monoxide,  324 
chimney  gases,  323 
incomplete  combustion,  323 
moisture  in  air,  326 
water  in  fuel,  322 
Losses,  stray,  326 
Low  water,  boilers,  144 


M 


Mabery,  C.  F.,  442 

Mahler  bomb  fuel  calorimeter,  *245 


456 


INDEX 


Manholes,  113 
Manometer,  305 
Marine  boiler,  122 
Marks  and  Davis,  44,  57 
Mass,  unit  of,  15 
Master  controller,  *220 
Material,  for  oil  tanks,  429 

of  commercial  furnaces,  160 
oil  tanks,  416,  421 
Maximum,  efficiency,  flue  gas  analy- 
sis for,  340 

Measurement,  of  oil,  205,  310 
of  steam,  302,  *305 
of  temperature,  31,  35 
water,  *74 
Measuring,      apparatus,      economy, 

*197,  *396 
atomizing    steam,    method    of, 

369,  374 
gage,  oil,  *206 
stack  temperatures,  method  of, 

369 

Mechanical  atomizer,  168 
Mechanical    atomizing    advantages 

of,  177 
burners,     Babcock    &    Wilcox, 

184,  *185,  *186 
boiler  tests  with,  358 
capacity  of,  182 
draft  for,  176 
efficiency  of,  *181 
installed    under     B.     &     W. 

boilers,  *178 
Lodi,  184 
number  of  burners  required, 

187 

pressure  for,  176 
regulation   of,    187,    (see  also 
Mechanical    atomizing    oil 
burners) 

temperature  for,  176 
tests  of,  180,  187 
combustion  of  oil  by,  182 
disadvantages  of,  179 
draft  required,  176,  188 
in  marine  practice,  183 
in  stationary  practice,  183 
oil  burners,  174,  393 
Coen,  *176 


Mechanical    atomizing    advantages 

of  oil  burners,  Dahl,  175 
Koerting,  *174,  175 
Moore     Shipbuilding     Com- 
pany, 175 
Peabody, 175 

operation  at  high  capacities,  184 
pressure  required,  176,  187 
quantity  of  oil  burned,  179 
temperature  required,  176 
Mechanical,  energy,  21 

Engineers,  American  Society  of, 
70,  219,  289,  308,  311,  329, 
332,  333,  359,  414 
equivalent  of  heat,  58 
horsepower,  435 

Melting  alloys,  temperature  by,  36 
Men  required  for  oil  firing,  226 
Mercurial  thermometers,  37 
Mercury  column,  23 
Merit   automatic    regulators,    *219, 

*220,  *341 
Meters,  air,  399 

flow  of  steam,  *304 
recording,  399 
steamflow,  68,  399 
Venturi,  *343 

Methods  of  sampling  petroleum,  133 
Mexican  oil,  139,  187,  387,  443 
Milwaukee  boiler,  *116 
Mines,  California  State  Bureau,  411 
U.  S.  Bureau  of,  235,  242,  299, 

411 
Mixer,  inside,  burners,  166 

outside,  burners,  168 
Moisture,  in  air,  loss  due  to,  326 
in  coal,  223 
in  exhaust  steam,  397 
in  oil,  methods  of  determining, 

236 

in  petroleum,  129 
in  steam,  82,  89,  90,  93 
in  wet  steam,  82 
Molecular  weight,  281 
Monoxide,  carbon,  loss  due  to,  324 
Moore  &  Company,  Chas.  C.,  379, 

380 

Moore   automatic   regulators,    *216, 
*217,  *218,   *331,  360,  384 


INDEX 


457 


Moore  automatic  regulators,  boiler 

room  efficiency  with,  361 
operation  of,  361 
results  obtained  with,  361 

Moore  regulator,  *12 

Moore  Shipbuilding  Company,  me- 
chanical atomizing  oil  burn- 
ers, 175 

Motor  generator  sets,  New  Cor- 
nelia Copper  Company,  365 

Mud  drum,  113 

Myriawatt,  70,  71 

N 

National     Board     of     Fire     Under- 
writers 204 
Rules  and  requirements,  415 

National  Electric  Light  Ass'n.,   180 

Natural  Gas,  388 

N.  E.  L.  A.,  414 

Nelson  Oil  Heaters,  *213 

Net  boiler  efficiency,  327,  332 

New  Cornelia  Copper  Co.,  360,  *366 
best  economy,  364 
boiler  efficiency,  360 
cooling  pond,  *366 
load  efficiency  curve,  *365 
maintaining  economy,  362 
motor  generator  sets,  365 
turbine  room,  *367 
type  of  equipment,  360 
vacuum  obtained,  363 

Newton,  Sir  Isaac,  15,  43 

Newton's  Laws  of  Motion,  15 

New  York  City  rules  for  installation, 
426 

Nipple,  sampling,  steam  calorimeter, 
93 

Nitrogen  content,  flue  gas  analysis, 
274 

Noble,  G.  Chester,  380 

Number  of  steam  electric  power 
plants,  391 

Nusselt,  Wilhelin,  109 

O 

Object  of  boiler  tests,  307 
Odor  of  petroleum,  126 
Ohio  oil,  443 


Oil  (see  also  Fuel  oil,  Petroleum) 
accumulators,  423 
air  required  per  pound,  259,  435 
analysis,  310,  443 
atomizing    steam    per    pound, 

*375 

Austrian,  443 
barges,  424 
boiler    horsepower    per    barrel, 

434 

Borneo,  443 
B.t.u.  per  barrel,  436 
B.t.u.  per  pound,  436,  443 
Bureau  of  Mines  instructions  for 

sampling,  299 
Bustenari,  442 
California,  387,  442,  443 
calorific  value  of,  443 
Campina,  442 
carriers,  424 

changing  from  coal  to,  221 
coefficient    of    expansion,    206, 

434 

heat  transfer,  213 
Colombian,  139 

combustion  of  one  pound  of,  293 
comparison  with  coal,  *222 
composition  of,  443 
continuous  sampling,  300 
conveyors,  424 

correction  for  temperature,  208 
crude  (see  Crude  oil),  cycle,  10 
data,  434 
distillation,  239 
fields  of  California,  *386 
filters,  422 

fire,  how  to  light,  196 
firing,  men  required,  226 
flash  point  of,  443 
flow  of,  through  burners,  379 

orifices,  *380,  *381,  *383 
flue  gas  analysis  from,  275 
for  cooking,  424 

heating,  424 
gallons  per  pound,  437 
gravity  of,  227 
heating  of,  432 

value   of    242,    434    (sec   also 

Heating  vulue  of  oil) 


458 


INDEX 


Oil,  influence  of  temperature  on  flow 

through    orifice),     *383 
Italy,  443 
Japan,  442 
Java,  443 
kw.-hr.   per  barrel,    *353,   359, 

364 

latent  heat  of,  434 
measurement  of,  205,  310 
measuring  gage,  *206 
Mexican,  139,  187,  387,  443 
mixed  samples,  301 
moisture  in,  335,  236 
Ohio,  443 

Pennsylvania,  442,  443 
pipe  lines  of  California,  *386 
piping,  215,  423,  425,  431 

standpipes,  423 
pressure,     relation     to     steam 

pressure,  *377,  378 
production,  diagram  of,  *391 
pumps,   *207,   *208,  209,   *210, 

*212,  431 
receivers,  423 
quantity  burned  per  h.p.  per 

hour,  258 
required  to  keep  a  boiler  hot, 

359,  378 

Russian,  442,  443 
sampler,  308 
sampling  of,  299 

with  dipper,  299 
service  tanks,  205 
specific  gravity,  436,  437,  443 

heat,  213,  434 
standards,  436 
steamers,  424 

still  with  hood  for  water  deter- 
mination, *238 
storage,  426 

tanks,  10,  202,  *203 

attachments,  205 

rules  for,  204 

size   of,    203    (see   also  Oil 

tanks) 

strainers,  422 
tank  steamer,  *412 
temperature  of,  195 
Texas,  443 


Oil  to  produce  one  h.p.,  435 

use  of  in  locomotives,  140 

valves,  423,  425 

velocity  of,  in  heaters,  213 
pipes,  215 

Venezuelan,  139 

viscosity  of,  434 

water  determination,  237 

weighing  of,  298 

weight  per  barrel,  434,  436 
gallon,  434,  436,  437 

West  Virginia,  443 
Oil  burners,  192,  215,  338 

application  of  test  data,  384 

atomizer  type,  166 

Best,  *171 

chamber  type,  166 

construction  of,  425 

drooling  type,  166 

fan  tail  type,  166 

Fess,  168 

function  of,  104 

Hammel,  166,  *167,  361,  378 

home-made,  169,  *173 

injector  type,  166 

installation  of,  425 

Leahy,  *169,  382 

Lockett,  *172 

mechanical  atomizer,  168 

mechanical  atomizing,  *11,  393 
(see  also  Mechanical  ato- 
mizing oil  burners) 

number  per  boiler,  372 

oil  pressure,  379,  382,  *383 

Peabody,  *168 

pressure- jet,  174 

relation  of  steam  and  oil  pres- 
sure, ?382,  *383,  385 

rose  type,  166 

rules  for,  432 

Staples  and  Pfeiffer,  *10 

steam  pressure,  379,  382,  *383 

Tate-Jones,  *170 

tests  with,  380,  *382,  *383 

Wilgus,  *172 

Witt,  *170 
Oil  burning  appliances,  202 

average  plant  efficiency,  353 

best  recorded  results,  359 


INDEX 


459 


Oil  burning,  boilers,  capacity  of,  393 
large    combustion    chamber, 

393 

draft  required,  339 
economies  in  ,  351 
equipment,    rules    for    installa- 
tion, 415,  426 
furnace  arrangement,  337 

interior,  *338 
plants,  installation  of,  433 

operation  of,  433 
regulation  of,  343 
relation  between  furnace  burner 

and  draft,  340 
tests,  351,  357,  358 
at  Long  Beach,  368 
miscellaneous,  368 
Oil  fired  boiler  room,  *107 
Oil  fired  boilers,  code  for  tests  for, 

332,  333,  336 
Oil  furnaces,  155,  192 
air  admission  to,  156 

supply  for,  103,  105 
area  of  air  openings,  159,  160 
arrangement    of     checkerwork, 

*156,  *157 

efficient  construction  of,  103 
excellent,  *158 
former  type,  *157 
fundamentals  of,  100 
location  of  air  openings,  159 
operation  of,  104 

Oil   heaters,    10,    *207,    *208,    *212 
Coen,  *214 
heat  transfer  in,  435 
heating  surface  required,  213 
Koerting,  *214 
Nelson,  *213 

Staples  and  Pfeiffer,  *212 
velocity  of  oil  in,  213 
Oil  tanks,  auxiliary,  425 
capacity,  427 

capacity  and  location,  416,  419 
construction,  416,  421,  429 
controlling  valves,  418 
enclosure  of,  426 
fill  pipe,  422 
filling  pipes  for,  *67 
fire  extinguishers,  418,  432 


Oil  tanks,  gauge  glasses,  423 

indicator,  418,  422 

location  of,  426 

material,  416,  421,  429 

outside  fire  limits,  428 

pipe  connections,  418 

pumps  for,  418 

rules  for  installation,  415 

service,  427 

support  for,  417 

vent  pipe,  422 

volume  of,  207 

within  fire  limits,  428 
Oil  wells,  production  of,  139 
Open  heaters,  5 

Operation,     detailed,     Parr     Calori- 
meter, 246 

of  boilers,  141 

rules  for  efficiency,  189 

of  Moore  automatic  regulators, 
361 

of     oil     burning     plants,     433 

of  oil  furnaces,  104 

principle  of,   Parr  Calorimeter, 
246 

steam  boiler,  principle  of,  109 
Orsat  analysis,  274 

conclusions    on,    277    (see    also 

Flue  gas  analysis) 
Orsat  apparatus,  *273 

flue  gas  analysis,  271 
Orsat  totals,  275 
Orifice,  calibration  of,  for  measuring 

steam,  *306 
Orifices,   flow   of   oil  through,  *380, 

*381,  *383 

Outside  mixer  burners,  168 
Oxygen  content,  flue  gas  analysis,  274 

in  fuel,  284 

required  for  combustion,  284 


Pacific  Gas  and  Electric  Co.,  3,  *26 
*33,  *45,  *68,  *84,  *108, 
*190,  *193,  *203,  *207, 
*225,  *280,  *330,  *342, 
*382,  *392,  *393,  *395,  397 
Station  A,  San  Francisco,  *84, 
*108 


460 


INDEX 


Pacific  Light  and  Power  Co.,  187,  382 

Paraffin,  442 

Parker  boiler,  *119,  118 

Parr  Calorimeter,  *245,  *246 

correction  for  temperature,  249 
detailed  operation,  246 
explosion  of  charge,  248 
preliminary  precautions,  247 
principle  of  operation,  246 
taking  of  temperatures,  248 

Parr  Fuel  Calorimeter,  *245 

Parr,  S.  W.,  246 

Path  of  furnace  gases,  104 

Peabody  commercial  furnace,   *161, 
162 

Peabody,  E.  EL,  162 

Peabody  furnace,  *7,  356 

Peabody-Hammel    commercial    fur- 
nace, *163 

Peabody   mechanical   atomizing    oil 
burners,  175 

Peabody  oil  burners,  *168 

Pennsky- Martens    tester    for    flash 
point,  131 

Pennsylvania  oil,  442,  443 

Percy,  E.  N.,  156 

Petroleum,  124,  125 
asphaltum  in,  129 
Association  of  U.  S.,  229,  230 
burning  point,  *124,  128 
calorific  value,  127,  133 
chemical  properties  of,  126 
classification  of,  125 
color  of,  125,  126 
consumption  of,  138 
corrosion  from,  129 
density  of,  126 
effect  of  heat  on,  126 
ether,  442 
flash  test,  *124,  128 
impurities  in,  132 
lamp  oil  in,  129 
latent  heat  of,  127 
methods  of  sampling,  133 
moisture  in,  129 
odor  of,  126 

physical  properties  of,  126 
production  of,  138,  387 
refining  losses,  129 


Petroleum,  specific  gravity  of,  127 

specifications  for,  129,  130 

sulphur  content,  129,  132 

viscosity,  128 
Physical    properties    of    petroleum, 

126 

Pipe  connections  for  oil  tanks,  418 
Pipe  lines,  oil,  of  California,  *386 
Pipes,  fill,  430 

vent,  430 

Piping  for  oil,  423,  425,  431 
Pocket  CO 2  indicator,  277,  *278 
Potential  energy,  20 
Pound  force,  16 
Pound  of  oil,  gallons  per,  437 
Poundal,  16 
Power,  17,  414 
Power  Co.,  Arizona,  *216,  *217,  *218 

Sierra  and  San  Francisco,  *206 

Southern  Sierras,  270 
Power,  hydroelectric,  1 

shortage  of,  386 
Power  plant  design,  present  status, 

386 

Power  plant  diagram,  *4 
Power   plants,    steam    electric,    (see 
also  Steam  Electric  power 
plants) 
Power  test  committee,  A.  S.  M.  E., 

332 

Power,  water,  1 
Precautions,  boiler  operation,   142 

preliminary,   Parr   Calorimeter, 

247 
Pressure,  absolute,  22 

atomizing  steam,  *377 

bursting,  147 

conversion  of,  27 

for  mechanical  atomizing  bur- 
ners, 176 

gage,  22 

in  atmospheres,  60 

loss,  in  superheat,  Long  Beach 
steam  plant,  375,  *376 

oil,  in  oil  burners,  379,  382,  *383 

readings,  boiler  tests,  312 

required,  mechanical  atomizing, 
176,  187 

safe  working,  153 


INDEX 


461 


Pressure,  steam,  oil  burners,  379, 382, 
*383 

steam  and  oil,  relation  of,  in  oil 
burners,    *382,    *383,    385 

theory  of,  22 

units,  relationship  of,  25 

working,  147 

for  boilers,  141 
Pressure-jet  oil  burners,  174 
Pressures,  law  of,  in  draft,  251 

ratio  of  oil  and  steam,  *377,  378 
Prices  of  fuel  oil,  135,  136 
Principal  data  and  results  of  boiler 

tests,  336 
Problems,  400-409 
Process  of  distillation,  239 
Production,  of  fuel  oil,  135 
in  California,  124 

of  oil,  diagram,  *391 

of  oil  wells,  139 

of  petroleum,  138,  387 
Pulverized  coal,  388 
Pumps,  5,  399 

boiler  test,  *143 

centrifugal,  111,  399 

duplex,  111 

feed  water,  111,  6 

governor,  *209,  210 

feed,  422 

dry  vacuum,  9 

for  oil,  431 

for  oil  tanks,  418 

oil,  *207,  *208,  209,  *210,  *212 

reciprocating,  399 

wet  vacuum,  9 

Pumping  station,  San  Francisco,  *18 
Pyrometer,  *307 
Pyrometers,  expansion,  38 

radiation,  38 

Q 

Questions  and  Answers,  409 


"R" 

value  of,  47 
Radiation,  107 

from  boiler,  359,  378 
pyrometers,  38 


Railroad  Commission  of  California, 

411 

Railroads,  electrification  of,  140 
Rates  of  oil  and  steam  pressures, 

*377,  378 
Rating,  66,  71,  72 
Reading,   normal,   of  steam   calori- 
meters, 88,  *89 

sum  of,  blue  gas  analysis,  275 
Reaumur,  thermometers,  32,  34,  35 
Receivers,  oil,  423 
Reciprocating  engine,  8 
Reciprocating  pumps,  399 
Recorder,  CO2,  *272,  *279 
Recording  instruments,  200 
Recording,  meters,  399 

thermometer,  *280 
Records,  keeping,  200 
Redondo,  187 

Refining  losses,  in  petroleum,  129 
Regnault's    formula,    for    saturated 
steam,  96 

for  steam  constants,  96 
Regulation  of  air,  106,  189,  191 

of  atomizing  steam,  194 

of  draft,  106 

Regulation,  of  mechanical  atomizing 
burners,     187 

of  oil  burning,  343 
Regulator,  damper,  *218 

Moore,  *12 

automatic,    gain    in    efficiency 
from,  399 

automatic,  (see  also  Automatic 

regulators),    215 

Relationship,  of  pressure  units,  25 
Repairs,  boiler,  under  pressure,  144 
Report,  boiler  operation,   *342,  344 
Results,  comparative,  in  boiler  tests, 
349 

obtained,     with     Moore    auto- 
matic regulators,  361 

oil  burning,  best  recorded,  359 
Return  tubular  boiler,  *116 
Riveted  joint,  *150,  *151 

bursting  pressure  of,  152 

efficiency  of,  150,  154 

strength  of,  151 
Rogers,  E.  A.,  360 


462 


INDEX 


Rose  type,  oil  burners,  166 

Rules    for    efficient     operation,     of 

boilers,  189 
for  oil  burners,  432 
for  oil  storage  tanks,  204 
for  safety,  boilers,  141 

Russia  Oil,  442,  443 

Rust  boiler,  120 


S 


Safe  operation  of  boilers,  141 
Safety,  boiler,  rules  for,  141 
factor  of,  147 
in  boiler  installation,  *413 
valve,  *20 
valves,  *113 
Sampler,  oil,  308 
Samples,  oil,  mixed,  301 
Sampling,  nipple,  steam  calorimeter, 

93 

of  oil,  299 

of  oil,  Bureau  of  Mines  instruc- 
tions for,  299 
of  oil,  continuous,  300 
of  oil,  with  dipper,  299 
of  petroleum,  methods,  133 
San  Francisco  pumping  station,  *1S 
Station  A,  Pacific  Gas  &  Elec. 

Co.,  *84,  *108 
Saturated  steam,  Henning's  formula 

for,  97 

Regnault's  formula  for,  96 
relation    between    temperature 

and  pressure,  96 
total  heat  of,  96 
Savannah  Electric  Co.,  *178 
Saybolt,  *124 

water  indicator,  308 
Scales  and  tanks,  for  water  measure- 
ment, *296 
Scales,  for  tests,  *74 

platform,    water    measurement 

by,  296 
Scotch  boiler,  122 

air  spaces  in,  *160 
Sea  level,  example  of  chimney  design 

for,  259 
Seattle,  City  of,  *224 


Sellegries,  124 

Separating  steam  calorimeters,   91, 

*92 

Separator,  7 
Service,  of  oil  tanks,  427 

tanks,  oil,  205 
Shipping  Board,  U.  S.,  137 
Shredded  Wheat  Co.,  *341 
Shutting  down,  of  boilers,  146 
Sierra  &  San  Francisco  Power  Co., 

*206 

Siphon,  steam  gage,  *112 
Size,  of  oil  storage  tanks,  203 

of  steam  electric  power  plants, 

391 

Smokestack  (see  Chimney) 
Soot,  356 
Soot  blowers,  356 

effect  on  temperature  of  escap- 
ing gases,  359 
Sources  of  fuel  oil,  139 
Southern  California,  Edison  Co.,  *2, 
*3,  *6,  *43,  *46,  *67,  *83,  *101,  *102, 
*197,     *202,     *208,     *210, 
*279,     *282,     *303,     *368, 
*390,  *394,  *396,  *398 
Southern  Pacific  Co.,  71 
Southern  Sierras  Power  Co.,  270 
Specific  gravity,  131,  426,  442, 

of  oil,  443,  436,  437 

readings,  for  temperature  cor- 
rections, 438 
Specific  heat,  37,  442, 

formula  for,  442 

of  oil,  213,  434 
Stack  temperature,  372 

at  Long  Beach  Plant,  *374 

method  of  measuring,  369 
Stand-by  plants,  356 
Standard  Oil  Co.,  156 
Standardization    of    thermometers, 

40 

Standards,  Bureau  of,  39,  229,  411 
Standards,  oil,  436 
Standpipes,  oil  piping,  423 
Staples     and     Pfeiffer,     211,     *212 

oil  heaters,  *212 
Starting  up  boiler,  cold,  379 

time  required,  379 


INDEX 


403 


Station    A — San    Francisco,    Pacific 

Gas   &    Electric    Co.,    *84, 

*108 
Steam,  50 

atmoizing,    (.see   also  Atomizing 

steam) 

calibration  of  orifice  for  measur- 
ing, *306 
correction  for,   used   by   steam 

calorimeters,  92 
cycle,  3 
dry  saturated,  75,  (see  also  Dry 

saturated    steam) 
exhaust,  (see  Exhaust  steam) 
external  work,  63 
flow  of,  302 

flow  of  through  orifice,  303 
flow,  meter,  *304 
formation  of,  52 
generated  heat  in,  310 
generation,  107 
heat  of  liquid,  61 
internal  work,  63 
latent  heat,  62 
measurement  of,  302,  *305 
moisture  in,  82,  89,  90,  93 
Napier's  formula  for  flow  of,  303 
quality  of,  78 
saturated,    (see    also  Saturated 

steam) 

specific  density,  61 
specific  volume,  60 
superheated,  (see  Superheated 

steam) 

total  heat  of,  55,  63 
used   in   atomization,    302,    310 
wet,   75,   78,  82,    («?«  also  Wet 

steam) 
atomizing  burners,   boiler  tests 

with,  357 
boiler,    principle    of    operation, 

109 

calorimeters,  80,  86 
calorimeters,  barrel,  82 
chemical,  86 
compact  type,  *94 
conclusions  on,  93 
correction  for  steam  used  by, 

92 


Steam,     calorimeters,    easily     made 

type,  *87,  94 
electric,  90 

normal   reading    of,    88,    *89 
sampling  nipple  for,  93 
separating,  91,  *92 
surface  condenser  tank,  84 
tank,  82 
Steam   calorimeters,    throttling,    86, 

*87 

limitations  of,  90 
Steam  driven,  auxiliaries,  398 
Steam  electric  power  plants,   inter- 
connected, 392 
isolated,  391 
location  of,  389 
number  of,  391 
size  of,  391 
Steam     Engineering,     fundamental 

laws,  14 

Steamflow,  meters,  68,  399 
Steam  gage,  *22,  *23,  112 

siphon,  *112 

Steam  plant,  Long  Beach,  descrip- 
tion of,  368 
Steam  pressure,  gain  due  to  higher, 

396 

limit  of,  397 
relation   to   oil  pressure,    *377, 

378 

tendency  toward  higher,  395 
Steam  tables,  54,  57 
analysis  of,  58 
typical  page,  *59 

Steam  turbines,  8,  (see  also  Turbines) 
horizontal,  8 
impulse,  8 
reaction,  8- 
vertical,  8 
Steamer,  oil  tank,  *412 

oil,  424 

Steaming    mechanism,     boiler    effi- 
ciency as  a,  328 
Steel,  test  specimen,  *147 
Steam  correction,  superheated  steam, 

81 

thermometers,  40 

Still  with  hood  for,   determination 
of  water  in  oil,  *238 


464 


INDEX 


Stirling  boiler,  120,  *161,  162 
Stocks,  of  fuel  oil,  137 
Stoker,  fired  coal,  388 
Storage,  of  oil,  426 

tank,  oil,  10 

tank,  water,  3 
Strainers,  210,  *211 

oil,  422 
Strength,  of  boilers,  147 

of  boiler  shell,  148 

of  boiler  shell,  rules  for  comput- 
ing, 148,  149,  150,  151, 152 

of  riveted  joint,  151 
Sulphur,  content  in  petroleum,  129, 

132 

Summary,  heat  balance,  327 
Superheat,     determination     of,     81 

pressure   loss    in,    Long    Beach 
Steam  Plant,  375,  *376 

temperature  determination,  *81 

superheated  steam,  76 
Superheated  steam,  factor  of  evap- 
oration, 76 

Linde's  formula  for,  98 

quality  of,  79 

specific  heat,  *62 

specific  volume  of,  98 

steam  correction,  81 

tables  of,  65 

total  heat  of,  79 

U.  of.  C.  formula  for,  99 
Superheater,  7 
Supply  of  fuel  oil,  137 
Support,  for  oil  tanks,  417 
Surface  condenser,  9 
Swinging  load  boiler  tests  on,   378 


Table,  of  draft,  257 

of  economy  data,  348 
Tables,  steam,  54 

Tabulation  of,  flue  gas  analysis,  283 
Tagliabue,  C.  J.,  229,  230 
Tank  steam  calorimeter,  82 

surface  condenser,  84 
Tank  cars,  *202 

Tanks  and  scales  for  water  measure- 
ment, *296 


Tanks,  for  tests,  *74 
oil,  (see  Oil  tanks) 
oil  service,  205 
oil  storage,  (see  also  Oil  storage 

tanks) 

Tate- Jones  Oil  Burners,  *170 
Tea  kettle,  100,  102,  107 
Temperature,  absolute,  46 
by  color,  36 
by  melting  alloys,  36 
correction  for  Parr  calorimeter, 

249 

entropy  diagram,  *65 
for  mechanical  atomizing  bur- 
ners, 176 
heat  diagram,  53 
influence    of,    on    flow    of    oil 

through  orifice,  *383 
measurement  of,  31,  35 
of  escaping  gases  from  boilers 

in  service,  356 
of  oil,  195 

oil,  correction  for,  208 
readings,  boiler  tests,  312 
required,     mechanical    atomiz- 
ing, 176 

stack,  (see  Stack  temperatures) 
superheat,  determination  of,  *81 
taking  of  Parr  calorimeter,  248 
Temperature  corrections,  to  appar- 
ent deg.  Baume*,  441 
to  apparent  specific  gravity,  440 
to  deg.  Baume,  439 
to  specific  gravity  reading,  438 
Test  data,  application  of,  oil  burners, 

384 

Test  specimen,  steel,  *147 
Tester,  gage,  *19 

Pennsky     Martens     for     flash 

point,  131 
Testing,    method    of,    Long    Beach 

Steam  Plant,  369 
of  thermometers,  40 
Tests,     of     mechanical     atomizing 

burners,  180,  187 
oil  burning,  351,  357,  358 
oil  burning,  at  Long  Beach,  368 
scales  and  tanks  for,    *74   (see 
also  Boiler  tests) 


INDEX 


465 


Tests,  with  oil  burners,  380,  *382, 

*383 

Texas  oil,  443 
Theoretical,  air  required,  259 

draft,  252,  *255 

draft  formula  for,  254 
Theory  of  draft,  251 

of  pressure,  22 
Thermal  unit,  British,  44 
Thermocouple,  *31,  *38,  *39 
Thermodynamics,  first  law  of,  44 

laws  of,  42 
Thermometers,  31 

alcohol,  37 

Centigrade,  32,  35 

electrical,  38 

Fahrenheit,  32,  34 

mercurial,  37 

Reaumur,  32,  34,  35 

recording,  *280 

standardization  of,  40 

stem  correction,  testing  of,   40 
Thermometer  well,  *40 
Thirty-inch  vacuum,  25 
Thornycroft  boiler,  123 
Throttling    steam    calorimeter,    86, 

*87,  90 

Time,  unit  of,  15 

Total  available  draft  required,  267 
Transfer,  heat,  435,  109,  110,  107 
Tube  cleaners,  boiler,  146 
Turbine  room,  New  Cornelia   Cop- 
per Co.,  *367 

Turbines  (see  also    Steam  turbines) 
Turbo-generator,  auxiliary,  398 


r 


Unit  of  length,  15 

Unit  of  mass,  15 

Unit  of  time,  15 

Units,  fundamental,  15 

University  of  California,  270,  381, 

411 
U.  of  C.  formula,  for  superheated 

steam 
U.  S.  Bureau  of  Standards,  229,  411, 

437,    438,    439,    440     441 
U.  S.  Geological  Survey,  411 

30 


U.   S.    Petroleum   Association,    229, 

230 
U.   S.    Bureau  of   Mines,   235,    242, 

299,  411 

U.  S.  Shipping  Board,  137 
Utilization,  of  exhaust  steam,  398 


Vacuum,  24 

obtained,  New  Cornelia  Copper 
Co.,  363 

thirty-inch,  25 
Value,  of  "R"  47 
Valves,  432 

check,  112 

for  oil,  423,  425 

non-return,  112 
Valves,  safety,  *20,  *113 

stop,  check  and  blow  off,  *111 
Velocity,  16 

of    gases    through    water    tube 
boilers,  266 

of  oil  in  heaters,  213 

of  oil  in  pipes,  215 
Venezuelan  oil,  139 
Vent  pipes,  430 

for  oil  tanks,  422 
Venturi  meter,  *343 
Vertical  boiler,  117 
Vertical  steam  turbines,  8 
Viscosimeter,  *300 
Viscosity,  130,  434 

Engler    &    Saybolt    compared, 
434 

of  oil,  434 

of  petroleum,  128 
Volume  of  oil  tanks,  207 
Volume,  relation  of  weight  to,  flue 
gas  analysis,  281 

specific,  of  steam,  60 

specific,  of  superheated  steam 
Volumetric    proportion  of   commer- 
cial furnaces,  160 
Volumetric  water  measurement,  296 

W 

Wadsworth,  J.  M.,  129 
Warner,  J.  B.,  142 
Water,  50 


466 


Water,  column,  *110,  112 

draft  in  inches  of,  253 

feeding  to  boilers,  196 

gage,  112 

in  fuel,  loss  due  to,  322 

in   oil,    determination   of,    237, 
*238 

indicator,  Saybolt,  308 

low,  boilers,  144 

measurement,  *74 

measurement,  automatic  meas- 
urer, *298 

measurement,       by       platform 
scales,  296 

measurement,  scales  and  tanks 
for,  *296 

measurement,    volumetric,    296 

power,  1 

specific  heat  of,  59 

storage  tank,  3 

tube  boilers,  7 

tube  boiler  advantages  of,  116, 

117 

boilers,  draft  loss  in,  266 
velocity  of  gases   through, 
266 

weighing,  295,  309 
Watt,  James,  67 
Weighing  of  oil,  298 


Weighing  of  water,  295,  309 
Weight,  flue  gas  analysis  by,  279 

molecular,  281 

of  flue  gas,  per  pound  fuel,  290 

of  oil  per  barrel,  434,  436 
gallon,  434,  436,  437 

relation  of,  to  volume  flue  gas 

analysis,  281 
West  Virginia  Oil,  443 
Westphal  balance,  *231 

computations  of,  233 
Wet  steam,  75,  78,  82 

determination  of  moisture,  82 

quality  of,  78 
Wet  vacuum  pump,  9 
Weymouth,  C.  R.,  219,  359,  379 
Wilgus  Oil  Burners,  *172 
Witt  Automatic  Regulators,  *215 
Witt  Oil  Burners,  *170 
Woolworth  Building,  *261 
Work,  17 

Working  pressure,  147 
for  boilers,  141 
safe,  153 
Wrana,  King  &  Co.,  370 


Zero,  absolute,  46,  58 


I 


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